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What to Look for When Buying a Screen Printing Exposure Unit

Thu, 15 May 2025 13:58:42 -0500

Not sure which exposure unit is right for your screen printing setup? This guide breaks down everything you need to know—light sources, features, and what to avoid.

Top 5 Mistakes Beginning Screen Printers Make (And How to Avoid Them)

Tue, 06 May 2025 09:19:00 -0500

Starting your screen printing journey? Learn key tips to avoid beginner mistakes and level up your print quality.

What Screen Printing Supplies do I need to get started?

Thu, 01 May 2025 09:57:55 -0500

Are you eager to dive into the world of screen printing? This popular method offers endless possibilities for creativity and customization. Whether you are a DIY enthusiast or a budding entrepreneur, having the right supplies is essential. Knowing what screen printing supplies you need will set you up for success. In this guide, we’ll explore the must-have tools and materials to get you started on your screen printing journey. Let's unlock the creativity together! Feel free to let me know if you need any further assistance or adjustments!

Choosing the right conveyor dryer for screen printing

Fri, 18 Apr 2025 15:28:45 -0500

Conveyor dryers play a critical role in screen printing, ensuring that prints are cured properly and efficiently. Choosing the right conveyor dryer can be tough because there are many options to pick from. This article aims to guide you through the process of selecting the best conveyor dryer for your screen printing operations.

Understanding Conveyor Dryers

Before starting the selection process, it's important to know what a conveyor dryer is and how it works.

What is a Conveyor Dryer?

A conveyor dryer is a piece of screen print equipment designed to cure or dry printed garments efficiently. It features a conveyor belt that moves the printed items through a heated chamber, allowing the inks to dry or cure evenly. The key benefit of a conveyor dryer is its ability to handle high volumes of prints, making it an essential component in commercial screen printing operations.

How Does it Work?

The operation of a conveyor dryer is relatively straightforward. Once a garment is screen printed, it is placed on the conveyor belt. The belt then transports the garment through a chamber where it is exposed to controlled heat. The heat causes the ink to cure, bonding it to the fabric. This process is crucial for ensuring the durability and quality of the print.

Key Considerations for Choosing a Conveyor Dryer

Selecting the right conveyor dryer involves evaluating several factors to ensure it meets your specific screen printing needs. Here are some essential considerations:

1. Production Volume

One of the first things to consider is the volume of production. If you run a high-volume screen printing business, you need a conveyor dryer that can handle large quantities efficiently. Look for models with wider belts and larger chambers to accommodate more garments at once.

2. Belt Width and Length

The size of the conveyor belt is another important factor. A wider belt allows for more garments to be processed simultaneously, increasing your production capacity. The length of the belt determines the time the garment spends in the heat, affecting the curing quality.

3. Heat Source and Temperature Control

Conveyor dryers use different heat sources, such as electric, gas, or infrared. Each has its advantages and drawbacks. Electric dryers are easy to operate and maintain, while gas dryers offer faster heating times and are more energy-efficient. Infrared dryers provide uniform heat distribution, ideal for delicate fabrics.

Temperature control is crucial in preventing damage to garments and ensuring proper curing. Look for models with precise temperature controls and consistent heat distribution.

4. Energy Efficiency

Energy efficiency is an important consideration, as it impacts operational costs. Gas-powered dryers are generally more energy-efficient than electric ones, but they might have higher upfront costs. Consider your long-term energy usage and budget when deciding on the heat source.

5. Size and Space

Conveyor dryers come in various sizes, and it’s essential to choose one that fits your available space. Measure your production area and consider the dryer’s footprint to ensure it can be accommodated comfortably without disrupting your workflow.

6. Budget

As with any business investment, budget is a critical factor. Conveyor dryers range in price depending on their features and capabilities. Determine your budget beforehand and explore options that provide the best value for your investment.

Types of Conveyor Dryers

Understanding the different types of conveyor dryers can also aid in making an informed decision. Here are some common types:

Electric Conveyor Dryers

Electric dryers are popular due to their ease of use and maintenance. They are suitable for small to medium-sized operations and offer consistent heat distribution. However, they may have higher operational costs compared to gas dryers.

Gas Conveyor Dryers

Gas dryers are ideal for high-volume production facilities. They heat up quickly and are more energy-efficient, which can lead to cost savings in the long run. However, they require a gas hookup and may have higher initial costs.

Infrared Conveyor Dryers

Infrared dryers use infrared lamps to produce heat, ensuring even distribution. They are perfect for curing delicate fabrics and achieving high-quality prints. They are energy-efficient and operate quietly, making them suitable for various production environments.

Maintenance and Safety Tips

Regular maintenance is crucial to ensure the longevity and performance of your conveyor dryer. Here are some maintenance and safety tips:

Regular Cleaning: Keep the conveyor belt and heating elements free from debris and dust to prevent any operational issues.
Check Temperature Settings: Regularly verify that temperature settings are accurate to avoid under-curing or damaging garments.
Inspect Moving Parts: Ensure all moving parts, such as the belt and rollers, are in good condition and lubricated as needed.
Safety Protocols: Follow all safety guidelines provided by the manufacturer and provide training to staff to prevent accidents.

Conclusion

Choosing the right conveyor dryer for screen printing requires careful consideration of your production needs, available space, and budget. By understanding the different types of dryers and evaluating key factors such as production volume, belt size, heat source, and energy efficiency, you can make an informed decision that enhances your screen printing operations.

Investing in the right conveyor dryer will not only improve the quality of your prints but also increase your overall productivity. Take the time to research and select a dryer that aligns with your business goals and needs.

Printing Metallic Inks – Glitters, Shimmers, Metallics

Wed, 09 Apr 2025 09:44:04 -0500

When it comes to printing, the right ink can make all the difference. Imagine adding a stunning sparkle or an eye-catching shine to your designs. That's where glitter, shimmer, and metallic inks come into play. Each of these inks offers unique visual effects that can elevate your creations from ordinary to extraordinary.

The Manual Print Stroke

Wed, 10 Dec 2014 09:49:00 -0600

The print stroke is all about laying the correct amount of ink onto your garment with the least amount of effort and effort on your part and the printer’s. There are two ways to print on your squeegee for clean print strokes. If you have a press that’s too big for your operator, you’ll need to put in more effort to get a clean print. Shorter people can stand on the platform so that they can push the squeegee down and reduce the printing effort.

Prepping Your Screens for Press Setup

Wed, 10 Dec 2014 09:24:00 -0600

We've exposed our screens, dried them, and now we're ready to go to press.

Taking the time to properly prepare these screens before setup can save time (and headaches) during your production run. (Read the article Getting Started: The Screen)

Blocking Out the Screens
WHY: Screen filler, also known as blockout, is an added protection from ink leaking through pinholes and that strip of exposed fabric between the screen frame and the emulsion you’ve applied. This liquid is inexpensive and can be purchased from most full service suppliers.

HOW: Lay your exposed screen on a table with the print side up. Pour a line of screen filler around the perimeter of the screen, close to the edge of your emulsion. With a square of cardboard or plastic (credit card size) spread the screen filler to cover the exposed mesh between the edge of your emulsion and the edge of your screen frame. Continue spreading the screen filler inward, within an inch or so of the image area, to cover any discovered or undiscovered pinholes.

Be careful not to cover up your registration marks with screen filler, assuming you will use these marks when you register the screens on the press. You will tape over these registration marks on the print side of the screen once the graphic is lined up and you are ready to print the job.

Your technique will be to lay down a thin layer of screen filler around your screen. Allow the screen filler to dry on the screen completely. Drying should only take a half hour in even the most humid of shops. You can place your screens in front of a fan or in the open breeze of windows or your dock door to speed up the process.

To save a little money, even though screen filler/blockout is inexpensive, you can use your old emulsion. Even when emulsion no longer works on screens for exposing, it will still do the trick as a blockout product. Going the old emulsion route, allow the screens to dry completely. For best results, set your screens in the sun to harden this extra emulsion coat.

Taping Your Screens
WHY: To keep ink from leaking from the angle where the screen frame meets the mesh, we want to tape all four sides.

HOW: Lay your screen on a table, ink side up, just the way it will be loaded into the printer. With strips of tape the same length as each side of your frame, tape the angle where the mesh and screen frame meet. If you have not used screen filler, also tape a strip around the edges of the mesh, between our taped corner and the emulsion.

You can add another strip of tape around the frame of your screen, especially top and bottom, to protect the frame from ink. This will speed up cleaning after the job is done. Be sure that no wrinkles exist along the edge of the tape where ink will leak under and eventually escape onto your garments. It’s always a good idea to burnish down the tape edge that will come into contact with your squeegee to assure no ink leaks under your tape.

Taping the ink side of you screen should be all you need. No need to tape the print side under normal circumstances. Some printers will tape inside the screen right up to within an inch or so of the image. By doing this, you can pull the tape at the end of the run and have less screen surface to clean. This is a perfectly acceptable practice and a matter of personal preference.

When taping over the emulsion to save clean up time, start from the top (closest to you when the screen is set up on the press) and tape in horizontal strips toward the bottom. In this way, the squeegee stroke will not cause the tape to roll up under the squeegee pressure. (The overlap of the tape goes the direction of your print stroke.) If you push your squeegee rather than pull, reverse this process and tape from bottom to top. (Read the article: The Manual Print Stroke)

Be sure your tape completely covers at the corners where the tape strips meet. If necessary, add another short piece of tape at the corner to ensure a tight seal against ink leaking.

Some printers use masking tape, but masking tends to breakdown during production and leave tape residue in your ink. Masking tape will also tear in the seam between the frame and mesh due to squeegee pressure, and then leak ink around the sides of your screen. Better to use tape that is specifically made for screen preparation.

Tapes made for screen application are available from full service suppliers. Most of these tapes will have a solid blue or a checkerboard blue and white strip along one edge. Where you see the blue or checkerboard strip, there is little adhesive. The idea is to place the low adhesive portion of the tape on your screen frame and the other side of the tape onto your mesh. Over time, tape adhesive can build up on your screen frames and become sticky and messy. The low adhesive strip along one edge of the tape is made to reduce this buildup of adhesive.

When applying any of these tapes using a tape gun, be careful that the cutting edge of the tape gun does not tear the screen mesh. Most printers will pull off a length of tape and apply by hand rather than using the tape gun to directly apply to the screen.

During production, if you discover pinholes or ink leaks, use tape to block the print side of your screen. Masking tape will pick up ink from subsequent screens and during any wiping of the screen and transfer the ink to your garment, so not a good option. For larger areas, you can use your screen tape. For small pinholes, especially close to the image area, use pieces of Scotch tape to cover.

Much of our success in screen printing is in the prep work, far more than in the actually printing of each garment. In most of our shops, we have the printing part of production fairly well in hand. It’s your prep work that separates one shop from the next.

Finding the Right Exposure Time

Wed, 10 Dec 2014 08:55:00 -0600

First, there is no hard and fast rule for exposure times. Your time will vary. Each of us coats our screens with more or less emulsion, the age of our exposure bulb, the wattage of our unit, and the mesh we use can all impact exposure time. So, the trick is to find the best time for your particular shop.

We need a good point to start when determining the best time to expose screens. Let’s use dual cure emulsion as starting point. If you use fast exposing pure photopolymer emulsion, take these numbers as a percentage guideline, based on your particular exposure unit.

Sunlight exposure – 30 seconds
5000 watt metal halide – 1 minute
1000 watt mercury vapor – 4 minutes
1000 watt quartz halogen – 5 minutes
Unfiltered blacklights or grow lights – 5 minutes

Again, these are only starting points to give you an idea of where to begin your testing. An exposure calculator is your best bet to zero in on the best time.

Exposure Calculator
An exposure calculator is a film positive that comes printed with five or more identical images including fine lines and dots. Using our starting point exposure times above, we expose the film onto a screen and wash out as normal. After the screen is washed out completely, hold it up to a light and compare the different images. The one that is exposed the best, where the image looks the most crisp, is our target. A formula under that image will tell us our ideal exposure time.

Best Target Number X Test Exposure Time = Correct Exposure Time

Our actual exposure time multiplied by the number given under our ideal image will equal our best exposure time.

Step Wedge
Another less exacting method to test for exposure time is to do a step wedge test. Basically, you choose an exposure time you think will work for you. Let’s take three minutes as an example. Place a film positive on your screen, and then block most of the image with thin cardboard or construction paper (something that will totally block the light) leaving about 20% of the image showing.

Expose the screen for less time than our three minute guess. Let’s try two minutes. After two minutes of exposure, move the cardboard sheet down to reveal 20% more of the image and expose for another 30 seconds. Then, move the cardboard down the image and expose for another 30 seconds. This will be our three minute estimated exposure time. Move the cardboard two more times exposing 30 seconds each time. We have now tested our exposure for a window of two minutes to four minutes in 30 second increments. Wash out the screen and see which exposure washed out best with clean crisp edges. Your ideal time will be the least exposure time with the best washout of the image.

Video of Step Wedge - courtesy of Chromaline

Videos on Using an Exposure Calculator - courtesy of Chromaline

Coating Screens in Your Shop

Wed, 10 Dec 2014 08:30:00 -0600

How do I coat a screen with liquid emulsion?

Seems like it should be a fairly simple step one, step two, step three response. But ask any 10 printers how they coat their screens, and you might very well receive 10 different answers . Let’s take some of the mystery out of this process.

First, let’s assume we are using either dual cure or pure photopolymer emulsion. Our approach will be finding a method that is both efficient and effective. Some recommend a multiple coat method – one side, both sides, or coat-dry-coat. This multi-coat approach can be attributed to a couple of reasons. The screen printer (or the person who taught him) may have had experience with older diazo emulsion and struggled with shrinkage of the emulsion on the mesh causing pinholes. Or the printer has struggled with pinholes even using dual cure or pure photopolymer, and has fixed the problem by applying more emulsion as a type of band-aid approach.

Today, modern emulsions offer good coverage without the shrinkage experienced with earlier diazo emulsions. And if the issue is pinholes, proper degreasing and protecting the screen from contaminants is the real fix, not applying more emulsion to the problem. Extra emulsion means more material cost, longer coating and drying times, and more difficulty reclaiming the screens after production.

In this article, I’ll recommend you coat screens with just one pass on the print side and one pass on the ink side (watch the video). Just another opinion from a screen printer out there in the world? This method is based on years of production and being fast, efficient and effective. Coating one pass on each side of your screen should give you a quick and perfectly effective screen, and ready for a full production run.

1.) Pour your emulsion of choice into a scoop coater with at least 1” clearance from the inside of the screen frame on each side. (If the inside width of your screen is 18”, the scoop coater should be no more than 16” wide.) The sharp side of the squeegee will go against the screen mesh.

2.) Stand the screen up on a table and hold with your left hand (if you’re right handed). With your right hand (or vice versa) pick up the loaded scoop coater from the center, take care not to spill emulsion out of either end. The operator in the video is left handed, by the way, so don’t be confused.

3.) On the print side of the screen, place the scoop coater against the scoop coater toward the mesh until a bead of emulsion touches the fabric across the entire length of the scoop coater. Do not roll the scoop coater over so far that the flat plastic sides of the scoop coater rest against the mesh. Rolling too far forward may cause the scoop coater blade to pull away from mesh during coating and result in a heavy emulsion lay down or emulsion spilling out onto the mesh.

4.) Pull the scoop coater up the screen slowly, allowing the thousands of tiny openings in the mesh to be filled with emulsion. (Experienced printers who come to my classes always seem coat the screen as fast as they can pull the scoop coater up the fabric.)

5.) About 1” before the inside edge of the frame, stop, roll the scoop coater back to allow emulsion to pour back in, then slide the scoop coater up and then away from the mesh.

6.) Turn the screen around and repeat.

Any excess emulsion on the screen, on the sides of your coating stroke, can be carded off with a small square of cardboard or plastic. This will speed drying of the screen and prevent emulsion from dripping down onto another screen during the drying process.

Now, dry the screen in a horizontal position either in a professional or homemade drying rack with the print side down (just as the screen is placed in your printer). Print side down will give you a heavier deposit of emulsion on the print side of the screen so that you have a nice smooth surface touching the shirt being printed.

If you make a mistake in coating, it’s okay to clear any excess emulsion from the coated area with the sharp edge of the scoop coater. Screen coating is a very forgiving process, so your repaired coating job may not look perfect, but it will work perfectly well.

When you are finished coating your screens, pour the excess back into the emulsion container for reuse later. Wash out the scoop coater immediately with water and allow it to dry upside down on a towel. Coated screens will last about two weeks in a dark room or light-tight container.

Coating is one of the processes in screen printing that tends to frighten new participants. (I’ve witnessed many a shaking hand during this part of class.) Just remember that proper preparation and a simple inside and outside stroke will result in a quick, easy and perfectly functional screen, ready to load on your press.

Care and Handling of Screens

Wed, 10 Dec 2014 08:27:00 -0600

During day to day production, our screens are pretty durable tools. No kid gloves required. Common sense care, protecting the mesh from sharp edges and the like, is all that is necessary to keep our screens in the production process. Where we do need to take added care is during that window of time from degreasing and up until we expose the screens.

When screens are wet, from either degreasing or after coating with emulsion, they tend to attract dust, lint and other contaminants from the air. When these contaminants attach to a screen, you are inviting pinholes during production.

Going through the process, we care little about these common print shop contaminants before degreasing. But once a screen begins the process of being prepared for the press, diligence is required. After degreasing, it is important to dry the screen again as quickly as possible, preferably in a clean, dust-free room with a dehumidifier to speed the process. A wet screen will attract (and hold) more dust and contaminants than a dry one.

After degreasing, do not place you hands on the mesh area. Your hands have natural oils. Emulsion is based with water. Oil and water don’t mix. The oil from your hands can cause pinholes that open up during a print run. Once the screen has been degreased – hands off the mesh. (Read the article Screen Degreasing: Pinholes are the Enemy!)

It's important to make this screen preparation window as brief as practical. Coat screens as soon as possible after degreasing and drying. Dust and lint that collects on a degreased screen that waits in storage will result in pinholes later down the production road.

After coating with emulsion, again dry your screens again as quickly as possible. Just as with wet degreased screens, wet emulsion on screens will attract dust and lint from the air. Once the emulsion is dry on the screen, your cautious care can be reduced. At this point, your only real concern is light exposure. An emulsion coated screen needs to be protected from light to keep it from being prematurely exposed.

The end of the period of extra screen care is after you have exposed your screens and you have dried them completely. At this point, you are back in a position where you can treat your screen more casually. Dust, oil from your hands, and fabric lint in the air will not affect your completely prepped screens. You can simply wipe any obvious contaminants away from the mesh before production.

Screen Degreasing: Pinholes are the Enemy!

Wed, 10 Dec 2014 08:16:00 -0600

Screen degreasing is the most critical step in preparing your screens for the production process. A slip up here will compound problems further into the process. Proper degreasing will eliminate most pinholes, that will in turn eliminate much spoilage and downtime. Most pinholes are a result of either no degreasing or poor degreasing. And...

“Pinholes are the enemy!”

Pinholes are those tiny little holes that open up in our emulsion, usually during a print run, and leave little dots of ink on the printed garment. The more pinholes that open up, the more dots of ink that can ruin a printed garment.

New screens and reclaimed screens need to be properly degreased before coating with emulsion… every time. There are people in this industry who will tell you that degreasing is not necessary every time you process your screens. A huge fallacy is that you do not need to degrease screens after the first time you use them. This advice is totally, absolutely incorrect.

Dust, lint, oils, chemicals on your screen WILL cause pinholes.

New screens come to you with machine oil, oil from the hands of everyone who ever touched them, dust, lint and other contaminants. All this foreign matter on the mesh will impact adhesion of your emulsion and cause pinholes on the press.

Used and reclaimed screens also have these contaminants from your shop, and must be properly degreased. The degreasing step is an absolute necessity each time a screen goes through the reclaiming/coating cycle.

Most suppliers carry a professional degreaser and this product is fairly inexpensive. I’m commonly asked in classes, “Can I just use my grease-fighting dish soap from the kitchen?” The simple answer is “No.” Most if not all of these products have lanolin or other hand softeners, which introduce oil to the fabric, which totally defeats the purpose of your degreasing step.

If you are using indirect emulsion (dry capillary film applied to a wet screen), you will need to use an abrader the first time you degrease your screen. An abrader is a degreaser with “grit” to rough up the surface of your screen. The purpose is to give your capillary film, applied to only one side of your screen, a coarse surface for the film to adhere. After the first use of abrader on a new screen, go back to regular degreaser for any subsequent cleaning.

There are some in the industry who recommend you always start with an abrader even when you are using direct emulsion. My advice is, “Never, never, never do this.” An abrader creates tiny tears in the mesh, which over time may impact tension and be a source of holes opening up in the mesh. Use of an abrader offers no advantage for a shop using direct emulsion on their screens.

Simple Technique

Degreasing is an easy process. Wet your screen on both sides. Ideally from a spray bottle, apply a small amount of degreaser across the surface of the mesh. With a clean soft brush or non-abrasive pad, move in circular motion around the mesh creating light suds on the surface. Turn the screen and apply more degreaser. Repeat the circular motion creating suds again.

Allow the screen to stand for about 30 seconds before rinsing with water. Use standard water pressure. No power washer is necessary, and could cause contaminants to bounce back onto the screen during this rinse. Hose off not only the mesh but the frame as well.

Always keep your degreasing brush separated from any other brushes used in your washout sink, so as not to contaminate the screens with inks and other chemicals. Degreasing brushes must only be used for degreasing.

Allow the screen to air dry away from dust and lint. The wet screen can attract contaminants from the air, so an accelerated drying process using a dehumidifier is preferred. You can use a fan or set your screens near air flow in your shop, as long as you are confident that dust and contaminants are not being blown into the mesh.

5 Important Steps in Prepping a Screen

Wed, 10 Dec 2014 08:13:00 -0600

Though it may not be rocket science, prepping a screen for screen printing involves a few different variables. You must make special considerations for factors like mesh count, diameter and more if you want your printing efforts to yield acceptable results. Following are five considerations that are very important to effectively prep a screen that will enable maximum results when you’re printing.

1. Select the proper mesh count: The proper mesh count will help to determine the amount of ink that is deposited on the substrate onto which you are printing. Choose low mesh counts for special-effects inks such as glitter (25-40 mesh), reflective or puff type inks (110-125 mesh). Choose high mesh counts (200-305) for more detailed or soft-hand prints.

2. Select the desired mesh thread diameter: A thinner thread diameter for any given mesh count will reduce the overall fabric thickness of the mesh and allow more ink to be deposited onto the substrate due to lower flow resistance and larger open area. The thinner thread diameter results in larger mesh openings and, thus, makes printing easier. This becomes important when a clean, crisp image or detailed design is desired, as the thinner tread diameter provides a smoother surface to which the stencils can adhere.

3. Make sure your screen frames are clean, straight and level: Properly cleaned and leveled frames will help ensure that the printed image comes out crisp and clear. Personally, I prefer metal frames to wood, since metal frames last longer, resist warping and splintering and tend to hold the mesh tension longer. In addition, I also prefer retensional frames, since the mesh tension can easily be tightened or adjusted.

4. Tension the mesh properly: Follow the manufacturer’s instructions for the ideal tension recommended for the specific mesh being used. Make sure the tension is equal in both warp (lengthwise) and weft (crossways) to achieve uniform mesh openings. Once the ideal tension is achieved (measured in Newtons with a tension meter), tension the mesh in the frame, let it sit and then retension again if needed. Mesh often will stretch a little after the first tensioning hence the fact that letting it relax and then recalibrating the tension will more accurately achieve the ideal tension desired.

5. De-haze and degrease both sides of the mesh: De-hazing removes ghost images of previous designs, ink stains and other impurities that may have accumulated on reused mesh. Although it may not be necessary to de-haze each time a screen is reclaimed, depending on how much detail the next design requires, it is a good idea to de-haze periodically, perhaps after two or three jobs.

Degreasing is an important step before applying emulsion to the screen to remove oils, dust, fingerprints, and other grime that may have settled on the mesh. This step can improve the adhesion of the emulsion and prevent pinholes and other imperfections, which may show up if the emulsion is applied over dirty mesh. I recommend degreasing as a mandatory step in prepping the screen prior to applying emulsion. After degreasing keep frames in a dust-free environment until they are ready to be coated.

One last tip: Always consider the manufacturer of the products you are using as a resource that can help answer any questions or concerns regarding its products.

What to Look for When Buying a Manual Press

Wed, 10 Dec 2014 08:08:00 -0600

Anyone with a two car garage has the potential of being a screen printer. It’s the beauty and the curse of the industry. Easy for you to get involved, and easy for every other person with that two car garage as well.

You can compete with the biggest printer, as long as you learn the process, and do what is necessary to output a first quality product. The possibility and potential is there for anyone willing to put in the time and effort to learn.

The number of colors, a six-color press for example, means the number of screens that you can set up at any one time. Will you print mostly six-color jobs? Not very likely. The bread and butter of screen printing is one, two and three color work. But you will have the potential of printing most any job, including full color images on dark shirts if you buy a six color press.

The platen is the board where you place your shirt for printing. Some presses, even multiple color presses have only one stationary platen for printing. More commonly, you will see multiple platens. These platens will move around the press independently from the movement of the screens around the press. Presses come standard with adult size platens, and a common add-on purchase will be youth platens as well.

Platens move around the press for two reasons:
1.) To print a white underbase on a dark shirt, rotate the platen under a flash cure unit, and then back to print the others colors on top of the white underbase.
2.) Platens move so we can have someone else loading and unloading shirts while we print. A helper loading and unloading will speed up the process. During day-to-day printing though, most manual presses have a single operator, and automatic presses will commonly have two operators.

There is much discussion about micro-registration. Some presses have it and some do not. Registering your screens, one to another so a multicolor image lines up correctly, is more a function of a good set of films, tight screen mesh, and properly locating your multicolor image on each screen than anything else. In other words, setup begins with the screens, and not the press. (Read the article Exposing Multicolor Screens: Lining Up Images for Quick Set Up)

Many old time printers (who predate micro-registration systems) can set up presses very quickly without using micros. Can micro-registration systems speed your setup? Yes, but you can still learn to setup a press very quickly without. As with all things in this industry, use or non-use of micro-registration systems will be a matter of personal preference.

So what’s the best press to buy? First, you’ll buy what you can afford. Many avenues will lead to the same end product. And second, you’ll buy the press that allows the number of colors to best service your particular market(s) of choice.

And remember, whatever press you buy, you will likely keep and use it as auxiliary equipment when adding more machines to your production shop.

Choosing the Right Mesh and Halftone Dot

Tue, 09 Dec 2014 16:49:00 -0600

Monofilament mesh is the product you will see in nearly all screen printing shops today. As the term mono would infer, this mesh is composed of single polyester threads woven together.

The different mesh numbers are determined by mesh count. This is the number of threads per inch in your mesh fabric. Lower mesh counts (fewer threads per inch) translates to more ink lay down. So, an 86 mesh will lay down more ink than a 305 mesh. Different inks, different substrates, our graphic, the color of our garment, all impact the mesh count we use.

The Right Mesh for the Right Job

The mesh you choose will depend on 1.) the ink you choose to use, 2.) the garment you plan to print, and 3.) the graphic going on that garment.
Below are some basic recommendations based on inks and images:

30 Mesh: Glitter or Crystallina
60 Mesh: Athletic Print (football jerseys for example)
86 Mesh: Heavy Ink on Dark Garments, Puff Ink, Plastisol Transfers
110 Mesh: Underbase for Heavy Block Letters or Artwork
156 Mesh: General Prints on Light Garments
196 Mesh: Multi-color Prints on Light Garments, Jackets
230 Mesh: Underbase for Simulated Process, Suede Ink
305 Mesh: Process Inks for Light Garments, Simulated Process Overprints

Don’t let the list overwhelm you. In the average screen printing shop, you will have maybe five different mesh counts on hand, depending on the markets in which you sell.

Numbers May Not Match
The numbers you see above are common in the industry, but you might very well see numbers that are slightly different. For instance, your supplier might tell you they sell 158 mesh, and not 156. As long as you are very close, it’s all the same.

The reason for the close-but-different numbers is in the fact that mesh is manufactured in Europe and Asia. Since these products are made outside the U.S., they are measured in metric numbers and not inches. When the mesh is imported, the numbers are recalculated and the product relabeled. So, some numbers will be off by a one or two, but the products are virtually the same.

The Halftone/Mesh Formulas

Halftone dots are used to either offer the perception of a shade of the color you are printing, or to blend colors in process printing or simulated process printing. Since we are printing small dots, we must use the proper mesh count that will hold these dots and allow us to print them. Here’s how we determine both the mesh and the halftone dots we can hold and print.

Let’s start with the halftone dot. To determine the proper mesh to use with a particular dot, we multiply by 4.5.

Dot Size x 4.5 = Mesh Count

For example, let’s say we have artwork with 35 LPI (lines per inch) dots:

35 LPI x 4.5 = 157.5 Mesh Count

Your mesh needs to be at least 157.5 or higher to hold you 35 LPI halftone dots. 156 mesh is close enough. In fact, some instructors will tell you to use 4 rather than 4.5 as your multiplier, so there’s some wiggle room when doing this calculation.

Now, let’s assume we have a limited number of screens available, and for this job today the highest mesh count we have on hand is a 196. We can reverse our formula and divide mesh count by 4.5 to determine the maximum dot size we can hold and print on this screen.

Mesh Count / 4.5 = LPI

As another example:

196 Mesh Count / 4.5 = 43.5 LPI

The smallest dot we can print on our 196 mesh will be approximately 43.4 LPI.

Using the proper mesh is half the battle in screen printing. When it comes to printing halftone dots, proper mesh will be 90% of our production floor battle.

Artwork Terms from the Screen Printing Industry

Tue, 09 Dec 2014 16:38:00 -0600

There are some artwork terms that are specific to our purposes in the screen printing industry. These are the terms you should know and understand when talking with artists and with your screen printing staff.

Spot Color Most of what you see in garment screen printing is spot color. For example, on a white shirt you might see a black outline image with a color or two or three filling the image area. This is spot color, as opposed to a photographic reproduction. Clip art school mascot designs printing in two or three colors are good examples of spot color printing.

You are not limited to white shirts. Spot color images can be manipulated to print on any color garment, and will generally have an outline of either black or white ink, depending on the color of the garment. Shading with halftones and gradations of color within the spot color image are also common to give the illusion of additional printed colors and depth to your image.

Process Printing Process printing utilizes CMYK - Cyan, Magenta, Yellow and Black - and is most commonly printed on white garments. These inks are transparent and will take on the color of the fabric they are printed upon. A yellow print on a light blue shirt will result in a green image. That’s why, for CMYK, a white garment is your best option.

Simulated Process This is your best choice when printing full color images on any color garment. Unlike transparent CMYK inks, simulated process uses opaque plastisol ink colors such as lemon yellow and scarlet red, printed using halftone dots to simulate process printing. Most full color images you see on black shirts for instance will likely have been printed using simulated process.

At least a six color press is recommended for this type printing. And a Photoshop plug-in program, specific to garment printing, is recommended to create these full color separations as well.

Index Printing Unlike simulated process which uses halftone dots, index separations will use a series of square dots to create the image. Index printing is color hungry. In other words, to create a full color image, more than six colors will likely be required to achieve the same effect as simulated process. Index printing is commonly used to created a posterized effect from a photographic image.

Halftone Frequency - This means the number of dots-per-inch (DPI), also known as lines-per-inch (LPI). Frequency determines the size of the dots you are going to print. The bigger the dot, the easier it will be to hold these dots on the screen and print onto your garment. Manual printers will not commonly go above 55 LPI. Automatic printers will usually go no higher than 65 LPI.

Setting halftone frequency is done under the Advanced Settings option when you send your artwork to print. The default settings on your printer will be much higher and will not work for screen printing. This is a common error for new printers when they attempt to use halftone dots in a graphic for the first time.

Dot Shape - The dots we print are not perfectly round. Rather in garment printing, we will most often choose elliptical dots.

Dot Angle - Halftone dots are printed along a straight line unless we specify otherwise. It is important that we do not allow this straight line of dots to align with the straight lines of our screen. This alignment may result in a moiré effect, causing patterns to appear on your screen and in your image. Dot angle is set under your Advanced Settings tab when you go to print.

Tip: For your spot color designs and for simulated process printing, set the angles for all colors at 25.

If you are printing with process inks, set each color at a different angle so that the actual dots from one screen to the next will not align and cause a moiré pattern between colors.

TIP - The dot angles to set by color for process printing will be:

Cyan - 15 degrees
Magenta - 45 degrees
Yellow - 75 degrees
Black - 75 degrees

Registration Marks - These marks are printed on each film so that it is easier to align artwork and screens on the production floor. Most commonly registration marks will appear on all four corners of the image. But in screen printing, placing two registration marks, centered at the top and bottom of an image will allow you to line them up with a straight line down the center of your platen for a quick setup and a perfectly centered image on the garment.

Butt Registration - Artwork prepared with butt registration means the edges of each color are lined up with one another with no overlap.

Trapping - This means the colors in the graphic are slightly spread to hide under the black outline of your graphic. Trapping is most common when printing spot color images, and will help to speed setup. Be careful of too much trapping. This may cause your image to look muddy where the colors overlap. Limit trapping of your image to about 2 points.

Stroke - Increasing the outline thickness of an image is used to make the outline screen easier to line up on the press (by overlapping other colors). Increasing the thickness of the outline is commonly called increasing the stroke.

Screen Exposure Light Sources

Tue, 09 Dec 2014 16:17:00 -0600

Exposing a screen, directing ultraviolet (UV) light toward an emulsion coated screen is the singular purpose of an exposure unit. Many sources exist, and each has its place in the mix. Let’s talk about all your options for exposing your screens.

Sunlight

There is no better source for UV light than the sun. And even in the biggest shop, it’s good to know how to expose a screen using sunlight. You never know when you might have to improvise a little. Basically, you can sandwich: 1) glass 2) film positive 3) screen 4) foam covered in black cloth or a t-shirt, and 5) a board the same size as your screen frame. Expose to sunlight and you’re good-to-go.

Unfiltered Blacklight

Not to be confused with blacklights that are used to make posters glow, unfiltered blacklights will look like traditional fluorescent tubes. These lights are very close to the glass on such exposure units. While the least expensive of the professional units (or homebuilt units) unfiltered blacklight exposure units have their drawbacks.

The advantages are an inexpensive unit, and compact (tabletop) as well. If you are building a unit like this yourself, you can substitute grow lights for unfiltered blacklights.

Quartz Halogen

Backyard or work lights are often quartz halogen lights. This is a light source often used in homebuilt exposure units, set up just like sunlight exposure with the quartz halogen bulb suspended above the screen.

This is a pinpoint light source just as the balance of the exposure units we will discuss. Pinpoint light means all the light emanates from a single bulb. It is much easier to hold fine lines and halftone dots with pinpoint light as you will not experience the undercutting of your images with light coming toward your art and screen from all directions.

Mercury Vapor

Street lights are mercury vapor lights. The important thing to know about mercury vapor is something you’ve probably already witnessed when street lights flicker on at night and get brighter and brighter over 10 minutes or more.

These lights come on slowly and build in intensity, which means the light needs to be turned on and warmed up before you can expose a screen. There will be a shutter door shielding the light while you place your film positive and screen on the glass in the proper position.

A vacuum will commonly be a part of a unit like this. The vacuum will activate and pull the screen mesh tight against the glass of the exposure unit. The unit is then turned on, opening the shutter door and activating a timer. When the time expires, the shutter door will automatically close.

Metal Halide

Metal halide light sources operate much like mercury vapor and will be found on higher end exposure units. Smaller units will have 1000 watt metal halide bulbs and larger, more expensive units will be as high as 6000 watts or more.

You will see this light source as either a cabinet unit or as a free standing exposure unit with the light set up a measured distance from the vacuum table. Just as often on higher end machines, an electric eye on the unit will read the light intensity (in lumens) and time the exposure by this light intensity rather by counting seconds. Bulbs will lose intensity over time. A unit that reads lumens will allow for this loss and always give you the exact same exposure.

Best Option

Your best option? The highest wattage bulb you can afford, and again if it’s in your budget, a vacuum attachment that will hold your screen and artwork tightly against the glass. But as I constantly say about equipment and techniques in this industry, any exposure option will do the job for you. The difference will simply be in efficiency and productivity in your shop.

Understanding Your [Liquid] Emulsion Options

Tue, 09 Dec 2014 16:03:00 -0600

Diazo Emulsion Systems

Diazo emulsions actually replaced bichromate emulsion systems years ago. The advantages diazo has over bichromates:

1.) It is much safer to use because it is Mercury free (heavy metal)

2.) Has a much longer shelf life. Bichromate emulsions have a shelf life of up to 8 hours.
Which means it must be mixed every day. When diazo emulsions were introduced, shelf life was increased up to 6 weeks. This made it much easier to have active emulsion ready to coat. Screens could now be stored for weeks, or longer, before exposing.

Diazo emulsion is a proven stencil choice. It will image most everything thrown at it; it’s tough against conventional solvent based inks, as well as abrasion resistant and it reclaims easily.

But diazo emulsions do have their problems. One of the big complaints is that it stains the mesh. This is very true, however, a properly exposed screen will lessen the staining. Also, reclaiming soon after the screen has been used will also reduce staining. Another problem is that it has limitations on image quality such as fuzzy edges and fill-in. Again, true. But, in most printing applications it will perform adequately.

The main components, without giving away the formula, in diazo based emulsion are; poly vinyl alcohol, poly vinyl acetate. The diazo is what is added to the emulsion by the customer.

Dual Cure Systems

Basically, the name says it all; it is a system that uses two sensitizers. Typically, the second sensitizer is a diazo added by the customer. It has distinct advantages over a straight diazo emulsion. Such as...

1.) Higher solids content, but not always. Typical dual cure emulsions will be in the range of 30 to 45% solids.

2.) Wide exposure latitude. These emulsion systems are very forgiving on establishing an acceptable stencil.

3.) High resolution. It is possible to achieve 50 micron lines. (A human hair is about 75 microns).

4.) Wide variety of solvent resistance.

By using two different sensitizers in one emulsion, more bonds are formed to give better stencil strength and imaging. The emulsion without the diazo added is ultra violet reactive by itself, but the diazo must be added in order to create a stencil. Dual cure emulsions can, but not always, be used with water based and solvent based inks.

Ever wonder what is in a dual cure emulsion? They have polyvinyl alcohol, polyvinyl acetate but they also have expensive components like urethane acrylates, photo initiators, and diazo. These components will yield quicker build-up, faster exposures, and higher resolutions than a straight diazo emulsion system. They are also more difficult to manufacture and in turn cost more to buy. Active solids are pricey.

Pure Photopolymer Emulsion Systems

This emulsion is also called “one pot”. There is no need to add a diazo sensitizer. All you have to do is pop the lid and coat the screens. You don’t have to worry about the shelf life like you do with diazo. Typically, it will be possible to make stencils up to two years from the date of manufacture. Exposure times are much shorter than the other emulsions. Many times exposure can be counted in seconds versus minutes. You have to be careful of the speed. Because it exposes so fast also means that the exposure latitude (exposure forgiveness) is much shorter than a diazo sensitized emulsion. It is very important to zero in on the correct exposure.

Pure photopolymer emulsions can be coated to a very thick E.O.M. (emulsion over mesh) easily because the solids content can be up to 50% solids. This means fewer coats to achieve thick stencils. Another added benefit to this fast exposing emulsion is that there will be fewer pinholes as compared to other systems that use diazo.

A typical pure photopolymer emulsion system contains photoactive polyvinyl alcohol, polyvinyl acetate, urethane acrylate monomers and oligomers and photo initiators.

There you go three types of emulsions...but which one should you use?

Let’s compare the pros and cons:

Diazo

Inexpensive
Very good resolution
Excellent durability
Lower solids
Shelf life: 4 to 6 weeks

Dual Cure

Moderately priced
Excellent resolution
Very good durability
Moderate solids content
Shelf life: 4 to 6 weeks

Pure Photopolymer

High priced
Very good resolution
High solids
Good durability
Shelf life: 1 to 2 years

The things to think about that should dictate what emulsion system to use is “What are you trying to print?” “What is the resolution that is needed?” and the most important question to be asked is “What type of ink is to be used?” All three systems have a product that will work for your application. When in doubt, ask your distributor.

Mesh Tension and the Impact on Your Print

Tue, 09 Dec 2014 15:17:00 -0600

Tension of your mesh is measured in “Newtons”, or more specifically, Newtons per centimeter. To measure tension, a weighted Tension Meter is rested on the fabric and the deflection (how much the fabric “gives”) is denoted by number. For example, 25 Newtons is a good tension for garment printing.

To determine the tension of a particular screen, lay the screen on a flat surface with the print side (mesh side) up. Looking at the screen from the top (the narrow side), place the meter in the center of the screen so that you can see the face of the meter. The needle will point to the number that will correspond to the tension of the mesh from side to side.

Now, move to the side of the screen (long side) and place the meter so you can see the face. This will tell you the tension of the mesh from top to bottom.

The ideal tension will be in the 25 and up to the 35 Newton range. There are special high tension mesh products available, but for garment printing, I personally feel these higher tensions are a bit of overkill and unnecessary. And, high tension mesh is very difficult to use when printing by hand on a manual press.

As a rule of thumb:

25 Newton mesh will give you an excellent tension for all types of printing

15-20 is acceptable

10 Newtons and below, your screen should be re-stretched

A tension meter will cost approximately $500.00 and it is not a required product when you are first getting started, but should be on your wish list. If you opt to use retensionable frames, a tension meter is absolutely necessary to achieve proper mesh tension during the stretching process.

Low Tension

So what’s the big deal about having screens with proper tension? There are two issues that may occur when you use screens with too soft mesh. These are (1) fabric wave, and (2) mesh release.

Fabric wave means, as you apply pressure and pull or push the squeegee across the screen and shirt, a small wave of screen mesh may form in front of the squeegee blade. On the bottom side of the screen, this wave of fabric may fill with ink as it passes over the image, and then smear ink onto the garment when the squeegee reaches the edge of the graphic.

The more common issue is mesh release. Printing with the preferred method of off contact, the only place the screen physically comes into contact with the garment is along the sharp edge of the squeegee blade. If your screen mesh is too soft, the mesh will not release from the garment as you pull or push the squeegee across the image. When the mesh does release, often when you lift the screen, the ink on the shirt will try to hold onto the screen mesh, causing a rough finish to your print.

On a multi-color job, soft mesh will stick to the previous colors on the shirt, and the ink picked up will begin to build up on the backs of your subsequent screens. In short order, your prints will start to appear muddy around the edges and where colors touch within your image.

When printing dark garments, poor screen tension can be doubly troublesome. The ink from the white underbase print is pulled up with the screen, and then flash cured into that position. My best analogy is seeing a thousand little mountain peaks standing up on the shirt. Under a microscope, the surface would look like the Alps. When colors are printed on top, the print feels very rough, or worse, hundreds of tiny white specks show throughout the print area where the white underbase peeks through the colors.

To recap, when a print feels rough, it is almost always caused by a screen with poor tension. (I get this phone call from screen printers all the time!) A tight screen will give you a crisp, sharp image. And on a manual press, a tight screen will cause far less printing fatigue during the process.

Squeegees and Your Printing Options

Tue, 09 Dec 2014 15:09:00 -0600

Most in our industry will pinpoint the screen as the most important tool in the printing process, but the squeegee will come along as a close second. The squeegee, the durometer (hardness), the angle and the pressure will have the next greatest impact on the appearance of your final printed product.

In garment printing, the squeegee blade will most commonly be polyurethane. Blade material can be cut to your specified length, either by your supplier or by yourself in your own shop. For manual printing, the blade and squeegee holder are often cut to length in a single process from a larger fully assembled squeegee. Squeegee blade material is also readily available from suppliers for you to cut and attach to the handle yourself. Finished squeegees and separate blade materials are almost always purchased by the inch and to your specification.

Squeegees have several functions:
1.) Pushing ink through the screen and onto your garment. The amount of ink forced through the screen is determined by the mesh size and the ink viscosity (thickness).
2.) Causing the screen mesh to come into contact with the garment. This contact will also be affected by screen tension and the off-contact distance between the screen and the platen.
3.) Sheering the excess ink from the print area on your screen. By sheering away the ink from the print area, no ink is left in the screen that might pull the ink on the garment back up into the screen. Lack of proper sheering of the ink from the print area can cause an uneven lay down of ink and a rough surface to your finished print.

Durometer
Durometer refers to the hardness of the squeegee. Durometer affects the amount of printing force you can apply to the screen and garment. Softer squeegees result in less force than harder ones. There are three most common categories of squeegee blade durometer.

Soft (approximately 60 durometer and below) squeegees will be used when you want a heavier lay down of ink. A soft durometer squeegee can be used for inks such as puffs, where a heavy deposit of ink is required to achieve the puff effect. You might also select a soft squeegee for fabrics that require a heavier deposit of ink such as fleece.

Medium (approximately 70 durometer) squeegees are a middle of the road option, and will be used for general printing. This will be the tool of choice for most of your day to day production.

Hard (approximately 80 durometer or higher) squeegees will lay down the least amount of ink and are most common for printing process and simulated process jobs when fine lines and halftone dots are needed. You might also select a hard squeegee based on the fabric substrate (such as nylon jacket material), where the ink will set on top of the fabric, and therefore require less ink for the job.

Multi-durometer squeegee blades (70/90/70 for example) are made of two or three layers of different durometer squeegee material. A harder blade will generally be sandwiched in the center of softer squeegee material to lessen the “give” of the blade. This layered blade is most common for process and simulated process work. The stiff center will help in the sheering of ink, while the softer outer edge will lay down slightly more ink. You’ll see these multi-durometer squeegees in many automatic shops, as well as manual shops for fine detail work.

Profile
Blade profile is the shape of the actual squeegee printing edge. A square profile is most common in garment printing, and provides the maximum ability to sheer the ink from the print area of the screen. Round squeegees provide a heavier lay down of ink. There was a time in textile printing when rounded blades were used for printing inks such as puffs, to maximize lay down of ink. Most printers today will opt for a softer but square edged blade for heavy ink deposits.

Pressure is the downward force you apply to the squeegee blade. In automatic printing, this is a set adjustment. In manual printing, it is a "feel" you will develop over time and with experience. There is a balance that must be achieved. You must apply enough pressure to sheer the ink from the screen, using only the sharp edge of the squeegee blade. Too much pressure and the blade will "roll over", and you will be printing with the flat side of the blade rather than the edge. The result will be either too much ink lay down, or ink being left in the print area of the screen instead of on the shirt. A softer squeegee blade will tend to "roll over" more than a harder blade.

Squeegee Care
It is important to thoroughly clean your squeegees. Most printers will clean the blade and handle with a solvent solution right after printing. Take extra care in cleaning the area where the blade meets the handle.

It's a good idea to reserve particular squeegees to be used with particular ink colors. This will save you spoiled shirts and spoiled ink when red ink from under the squeegee blade suddenly appears in the white ink in the screen.

If you use a solvent tank or tray, do not soak the blades for extended periods of time. This soaking of the blade material can cause swelling or distortion of the blade, ruining it for future use.

Store squeegees either on a hanging rack or in a handle down/blade up position on a shelf. Never store squeegees resting on the blade. The blade will eventually warp or distort and become useless.

If you discover nicks in the squeegee blade, showing up in your print as a heavier deposit line, you have two choices. You can sharpen the blade with either a professional sharpening device or a homemade sharpener created from fine sandpaper attached to a board. Or you can remove the blade from the handle and replace it with new blade material. Replacing the blade is the most common option.

Today, there are ergonomically shaped squeegees, blades created for pushing rather than pulling, and new approaches to the process with each coming trade show. But for now, the most common approach will be the standard wood handled device, chosen simply by the proper durometer to match your chosen ink and substrate.

Frame Options: From Wood to Retensionable

Tue, 09 Dec 2014 14:37:00 -0600

Most commonly the term “screen” refers to a frame with screen mesh attached. There are three options available to screen printers when it comes to the frames we choose.

Wood Frames

Today, wood frames have glue holding the mesh in place. Most commonly, mesh is pulled in all directions via a pneumatic device, and the mesh is then glued across the face of the frame.

While screen printers in the past stretched their own screens, and some certainly still do, it is much more common today to buy your screens already stretched with fabric. The increased cost is nominal (for frame and mesh), and when you factor in the time involved in stretching your own screens, it makes more sense to buy frames pre-stretched. When mesh becomes torn or loses tension, the frames can be re-stretched with new fabric by most frame suppliers. (Read the Article: Mesh Tension and the Impact of Your Print)

Static Aluminum Frames

The second frame is static aluminum. Just like the wood frame, static aluminum features mesh that has been stretched and glued in place. The term “static” refers to the fact, just like wood frames, that the mesh has been stretched and that same mesh cannot be re-stretched to maintain tension. In fact, through use, both wood and static aluminum frames will lose tension over time.

The cost of static aluminum is generally just a few dollars more than wood, but these frames are lighter to work with in the shop and on the press. Just as with wood, static aluminum frames are almost always purchased with mesh attached, and can also be re-stretched as necessary by your screen supplier.

With pricing of static aluminum frames now more in line with wood frames, the aluminum frame is becoming the industry standard in most shops.

Retensionable Frames

The third option is the retensionable frame. Just as the name infers, these frames can be re-stretched by you as necessary. As you use a screen, whether it be wood, static aluminum or retensionable, it will lose tension as a result of the constant pulling and pushing on the mesh by your squeegee. Wood and static aluminum screens will reach a point where it is not practical to use them any longer because of poor tension.

With retensionable frames, you can tighten the mesh on the frame. This re-stretching is accomplished by loosening the bolts holding the frames sides in position and then pulling the mesh taunt with a wrench.

Retensioning occurs only when a screen has been used, then reclaimed (emulsion removed). Trying to retension a screen with emulsion and an image will result in distortion of the image and potential cracking of the emulsion on the mesh. Screens for multi-color work would certainly become difficult to realign with one another if a retensioning of one or all screens is attempted.

After you go through this restretching process approximately five times, you will discover that the screen mesh will no longer lose its tension. This process of re-stretching and then the mesh maintaining its tension is called “work hardening”. After stretching and re-stretching a few times, the mesh will reach a point of work hardening where the mesh will no longer stretch. From this point forward, if you take care of the screen, you can literally use this stretched screen for years. While a retensionable screen can cost 2-3 times more than a wood or static aluminum frame, in the long run you will have a more economical product.

Here’s the trick though. In consulting with many screen printing shops, I will ask owners and managers how often they re-stretch their retensionable frames. The answer is most often, “We check our mesh tension each time the screen is reclaimed.” When I then go onto the production floor and ask someone in the screen prep department the same question, the answer is something like, “I can tell how tight the screen is just by feeling it.” Then as I press for an answer, “We’re really busy, so…” Bottom line, in many, many shops, the tension is never checked. If that’s the case, the expensive retensionable frame is no better than a wood or static aluminum frame.

You know who you are. If you are that person who will check the tension or make sure your staff checks the tension, these frames will save you money in the long run. If you treat these frames just like pre-stretched frames, your better off going with the less expensive wood or static aluminum.

Walk Through of the Garment Printing Process

Tue, 09 Dec 2014 14:05:00 -0600

From the biggest auto shop, to the single manual press in your basement, screen printing… is screen printing… is screen printing. With the proper techniques, you can print the exact same image in your own shop as any competitor, large or small.

Let’s take a quick walk through the entire process...

1.) Artwork

To start any job, we begin with artwork. We will either create our own artwork, receive artwork from a customer, or more likely, some combination of the two. This is always an area of difficulty for screen printers. Most of our customers have little understanding of what kind of artwork we need, or what we as screen printers are capable of reproducing on a garment. So, you’ll spend time at this point educating your customers. (Read the article Getting Started: Art and Film)

2.) The Screen

The screen is a weak point in the chain for many printers, cutting corners and “making it work” when in fact the wrong mesh is used, improper tension, or both! Get your screens right, and you’ll be ahead of most of the competition. (Read the article: 5 Important Steps in Prepping a Screen)

In the screen printing industry, you’ll hear debate about wood frames, static aluminum frames, and retensionable frames. As with many things in screen printing, all will accomplish the task. (Read the article Frame Options: From Wood to Retensionable )

3.) Coating the Screen

To make a screen ready for the press, we need to apply a photo-sensitive emulsion to the mesh. There are two primary options. The first is to apply a liquid emulsion to both sides of the screen using a scoop coater. This hand-held device is filled with emulsion, placed against the screen mesh and slowly pulled bottom to top, depositing emulsion as we go. The screen is then turned and the same process is repeated on the other side. The second option is to apply capillary film to a wet screen. Capillary film is in fact a dry emulsion on an acetate carrier sheet. (Watch the Video: How to Coat a Screen with Emulsion or read the article)

3.) Exposing the Screen

Ultraviolet light (UV) is what exposes our emulsion coated screen. Sunlight is the perfect source of this UV light. That’s why we wear sunscreen! There are a variety of UV light sources available for you to use.

The process in a nutshell is this: We place our film positive against the coated screen, and then expose it to UV light. Where the light touches the screen, the emulsion hardens. Where the light does not touch the coated screen (behind the black parts of our artwork), the emulsion stays soft. After exposing the screen to UV light, we remove the film positive and wash out the image with a gentle spray of water. (Read the article: Screen Exposing Light Sources, or watch the video: How to Expose a Screen)

4.) Printing Equipment

If you’ve ever visited screen printing shops or attended a trade show, you may have seen anything from one color manual machines to 14 color automatic presses. It all comes down to efficiency in the end. An automatic press is far better to print a 10,000 piece order, but that same automatic press is not your best choice to print a 24 piece job.

5.) Inks

Most screen printers use only plastisol ink. If you have any printed T-shirts in your dresser drawer at home, they are likely printed with plastisol. There is a common assumption that only heavy, plastic-like prints are plastisol, but this is not the case. Plastisol can be printed with a very soft “hand”, and is the ink of choice in the industry due to it’s ease of use. Plastisol will not dry in your screen when you walk away for five minutes… or five days! A real advantage when you’re wearing all the hats in your business.

6.) Squeegees

Squeegees come most commonly with a wood handle and a square plastic or rubber blade. Squeegees are purchased by the inch from your supplier, for all the different sized graphics you print. You will use a squeegee that is at least an inch wider than your image on each side. Squeegee blades come in different hardness, measured in durometers. Softer squeegees will lay down more ink, and harder squeegees lay down less.

7.) Adhesives

An adhesive is needed to hold your shirt in place while you print. A low spray adhesive that comes as either a mist or web spray. There is also a liquid adhesive used in the industry as well. (Read the article: Adhesives on the Press)

8.) Curing

All inks will need to be heat set. Plastisol ink needs to reach a temperature of approximately 320 degrees to cure. Your best option is to use a conveyor dryer. You lay the shirt, print side up, on the dryer belt and let it move into the dryer chamber. When the shirt exits the other end, assuming your dryer temperature and belt speed is correct, the garment is finished. You can wear it, wash it, fold it and box it. Once plastisol ink reaches curing temperature, it is completely cured, now and forever.

9.) The Process

The screen printing process is basically the same whether you’re printing in your garage or in a 100,000 sq ft facility filled with automatic presses and dryers. Learn the basics, and you can function perfectly well in both environments.

Getting Started: Inks and Supplies

Tue, 09 Dec 2014 13:50:00 -0600

Most screen printers use only plastisol ink. If you own any printed T-shirts at all, these are likely printed with plastisol. There is a common misconception that only heavy, plastic-like prints are plastisol, but this is not the case. Plastisol can be printed with a very soft “hand”. The term “hand” in our industry means how heavy the print feels. A light or soft “hand” means the print feels very thin on the garment. By printing through a higher mesh screen and/or thinning the ink with an additive, you can achieve this soft hand print with plastisol ink.

The advantage of plastisol inks over others is in the fact that plastisol will not dry in the screen. Plastisol must reach a temperature of approximately 320 degrees to cure. For the screen printer, this means we can walk away from the press to take a phone call, go to lunch, or even leave for the weekend. When you come back to the press, you load a shirt, pull the squeegee, and keep going. No other inks offer us this kind of flexibility. This is a huge benefit to small printing operations where you wear multiple hats in running your business.

There are a variety of other ink products such as puff, metallic, water base, discharge, etc. that will make you a more versatile printer for your customers. You ink supplier can provide you with all the specifics of how to use these specialty inks.

Adhesives

There are a number of adhesive options to lightly adhere your shirt to the platen for printing. One is a liquid that you spread across the platen and allow to dry. As you print and the adhesive loses its tack, a spray of water will reactivate the adhesive. This product is most commonly used with automatic presses.

Most manual shops and many automatic shops use one of two types of spray adhesives. Available in spray cans and purchased by the case, spray adhesive comes in either mist spray or web spray. Mist spray has the appearance of spray paint as it exits the can. Web spray comes out in a strand similar to a spider web. Mist spray tends to get into the air and stick to everything, including your hands, arms, clothing, and your press through the day. Web spray is more directional but some printers complain it is more difficult to clean up on the platens and press.

In the end, your choice is a matter of personal preference. You will meet printers who swear by one product or the other, but this is usually based on the product this particular printer started with in their first shop. All these adhesive products do the job equally well.

With our adhesives, we want to achieve a low tack adhesion of the garment to the platen so the shirt does not pick up with the screen, and to hold it in place to maintain registration for multicolor printing. You will likely get 6-12 prints before reapplication is necessary, depending on the garment. You will get a “feel” for when you need to reapply by how easily a garment is removed from the platen after printing.

Inks and printing supplies are the consumable products in the process for you. In other words, these are the products you will buy over and over again as they are consumed in the process of printing.

Getting Started: The Screen

Tue, 09 Dec 2014 10:58:00 -0600

There's a reason it's called Screen Printing!

The screen is critically important to the process. In fact, this is the weak link in the chain for many printers, cutting corners and “making it work” when the screen is your most important tool. Get your screens right, and you’re halfway home to a great finished shirt.

Once we have the art and we have output a film positive, we need to expose this film to an emulsion coated screen (watch the video: How to Coat a Screen). In this industry, you’ll hear much debate about whether to use wood frames, static aluminum frames or retensionable frames. As with many things in screen printing, all will accomplish the task at hand. The differences will be in efficiency, repeatability and your own budget.

You will start with a frame stretched with polyester mesh. There are a variety of mesh counts (number of threads per inch) with a variety of screen openings. The greater the size of the screen opening, the more ink flows through. Lower numbers, for example an 86 mesh, will allow more ink through than higher numbers, 305 mesh, as another example. 86 mesh has fewer threads per inch so the opening are bigger, allowing more ink to flow through. Your ink and your artwork will determine the proper mesh count (Here's how to use your artwork to find the proper mesh). Add to that, the tension of the mesh on the frame. For this overview, we will assume a frame stretched with proper tension.

Coating the Screen

To make a screen ready for the press, we need to apply a photo-sensitive emulsion to the mesh after the screen has been degreased. This degreasing step is very important, as a clean screen before coating will be more durable throughout the print run. Basically, degreasing the screen will wash away oil from your hands, dust and lint from your shop, and any other contaminants on the mesh. (Read the article Coating a Screen, or Watch the Video. Also, check out the article on The Care and Handling of Screens)

There are two ways to accomplish the coating step. The first is to apply a liquid emulsion to both sides of the screen using a scoop coater. This hand-held device is filled with emulsion, placed against the screen mesh and slowly pulled bottom to top, depositing emulsion as we go. The screen is then turned and the same process is repeated on the other side. A scoop coater should fit inside your screen with at least 1” clearance from the frame on each side. Just as with squeegees, scoop coaters are purchased by the inch.

One surprising part of screen coating for students who are already printing shirts, is that we will coat our screens in full room light. Coated screens need to be stored in a dark room or light-tight container as they dry and as we wait to use them, but the initial coating can be accomplished under normal room light. Now, bear in mind we will not coat our screens near windows with direct sunlight, but standard room lights will be perfectly fine.

The second method of applying emulsion to the mesh is by using capillary film. This emulsion is a dry product on an acetate carrier sheet. Capillary film is applied to a wet screen to activate the emulsion and cause it to stick to the mesh. A squeegee is used to press the capillary film against the wet mesh. After drying, the carrier sheet is peeled away leaving the emulsion on the print side of the screen mesh. A screen coated with capillary film will not be as durable as a wet emulsion coated screen since the emulsion is only applied to one side, so best suited for short runs.

Exposing the Screen

The reason we do not coat our screens close to windows with direct sunlight is because ultraviolet light (UV) is what exposes (hardens) our emulsion. Sunlight is the perfect source of this UV light. That’s why we wear sunscreen! There are a variety of sources of UV light available for screen printers, from unfiltered black lights to metal halide bulbs.

The process in a nutshell is this: We place our film positive against the coated screen, and then expose it to UV light. Where the light touches the screen, the emulsion hardens. Where the light does not touch the coated screen (behind the black parts of our film positive), the emulsion stays soft. After exposing the screen to UV light, we remove the film positive and take the screen to our washout sink. (Watch the video: How to Expose a Screen, or read the article: How to Find the Right Exposure Time)

After removing the film from the exposed screen, we should see a slightly different color of emulsion where the artwork blocked the light. Under low water pressure, with preferably warm water, we will rinse both sides of our screen, and then run water across the artwork area of our screen. Within 15-30 seconds, we should see the artwork area of our screen begin to wash out and be clear.

The screen is then dried using a blotting technique, vacuum or forced air. The emulsion remaining on the screen should be allowed to dry completely before we proceed.

At this point, the screen is ready to be taped up, loaded into our press, and filled with the proper ink color for the job. We’re ready to print!

Getting Started: Art and Film

Tue, 09 Dec 2014 10:10:00 -0600

To start any job, we need artwork. We have a few options. Depending on the target market, we’ll either create our own artwork, receive artwork from the customer, or more likely, some combination of the two. This is usually an area of difficulty for new screen printers, unless you happen to be starting your business as a graphic designer as well. Most of the customers who come to you will have little understanding of what kind of artwork we as printers need, or what we are capable of reproducing on shirts with screens.

Art Programs

First are the art programs. If you plan to use a PC for artwork, chances are you will use Corel Draw for your graphics. Just as likely you will use Adobe Illustrator if you are a Mac user. Both these programs are vector based. With a vector program, you will do all spot color work (blocks of color and line art) and special lettering effects. In vector programs, you can change the size of the image with no effect on the quality of the image.

The majority of custom screen printers, businesses who print for any customer in need of custom printing, do nothing beyond spot color and lettering effects for their customers. Most custom printed T-shirts you see today are produced with these spot color images.

If you choose to do any photographic images on shirts, you’ll need to use Adobe Photoshop as well. Photoshop, in both the PC and Mac version, is a raster (or pixel) based program. For photographic reproduction on a garment, you will likely purchase one of the automatic separation programs as well. Separation software will “look” at your full color image in Photoshop and automatically create the separations needed to reproduce the image on a shirt.

There are training courses via DVD, webinars and trade show seminars that will address each of these programs specific to screen printing. Generic training, say at your local community college, will spend much time discussing web design, etc., so training specific to the garment printing industry will be a real plus.

Film Positives

Once you have a finished piece of artwork that both you and your customer have agreed upon, we’ll need to create a film positive. This film positive will generally be a black image printed on clear acetate film. A three color design, red, yellow and black, will be output onto three separate films, all with the images in black. There are a variety of ways to create a film, but most operators today, both large and small, will use an inkjet printer for output.

Output Device for Your Film

If you plan to print any halftone dots (shades of color) you will need RIP software. By halftones, we’re talking about printing, for example, a solid green image, and also green in halftone dots to create a lighter shade of green, all from a single screen. You will also use halftone dots to give the illusion of depth in an image and to blend together two or more colors for a more colorful design with the fewest number of screens.

RIP is an abbreviation for Raster Image Processor. Inkjet printers, while giving you an excellent film positive to work with, are in fact full color printers. These printers always “think” they are printing in color. Halftone dots give the illusion of a shade of color. The inkjet printer will try to help you out when it sees halftones, and will print these dots in grey rather than black. Grey dots will not expose on your screen.

On the other hand, RIP software revolutionized the industry by “telling” your inkjet printer, “When you see halftone dots, print solid black dots.” And that is why, sooner or later, you will absolutely need RIP software to output film positives on an inkjet printer.

Be cautious here. You need RIP software that is specific to screen printing and film positive output. A RIP from an inkjet machine manufacturer will be a color management product and not for the purpose of outputting solid black dots. So when the salesman at the office supply store says he has RIP software, he’s referring to color management software, and will not likely even understand what you are trying to achieve by printing solid black dots. Color management software will not recognize your halftones. Your RIP software must be specific to film output.

You may already be using a laser printer for your film output, or such a device has been recommended to you. Will a laser printer work? Yes. Is it the best device? No. Output from a laser printer tends to not be opaque enough to easily expose a screen, so you will find yourself underexposing your screens to get the image to wash out.

Laser printers use heat during processing, so film positives from this device tend to shrink. This shrinkage will be of little consequence on one-color jobs, but registration of multiple colors can be very difficult using laser output. If you are already using laser, keep going as you are until you’re ready to upgrade. If you have yet to buy an output device, inkjet with RIP software is the product of choice today.

Remember, it is not necessary to overbuy inkjet printers. Most screen printers will never make films larger than 13x18, so an inexpensive Epson printer will do an excellent job. If you will be doing regular output more in the 17x22 range, a larger format (and more expensive) printer will be required.

Getting Started: Printing Equipment and Set-Up

Tue, 09 Dec 2014 08:35:00 -0600

If you’ve ever attended an industry trade show or opened one of the garment printing magazines, you’ve seen everything from one color manual machines to multi-color automatic presses. You can even build a press yourself if you’re handy enough, and achieve very similar results. This is the true beauty of the screen printing industry. You can achieve the same result from the least expensive to the most expensive equipment. It all comes down to efficiency in the end. An automatic press is far better to print a 10,000 piece order, but that same automatic press is not your best choice to print a 24 piece job. There’s a place for all.

“Anyone with a two car garage has the potential of being a screen printer,” I often tell students.

And it is absolutely true. You can compete with the biggest printer, as long as you learn the process, and do what is necessary to output a first quality product. The possibility and potential is there, but the effort will be all up to you.

The number of colors available on a press means the number of screens that you can set up at any one time. A four-color press has the potential of printing up to a four-color job. If you haven’t purchased a press yet, and you can afford the price, I highly recommend you purchase a six-color press. Will you print mostly six-color jobs? Not very likely. But you will have the potential of printing most any job, including full color photo quality images on dark shirts with a six-color machine.

Those full color images are beautiful to look at, and a great goal for you to aspire. But the bread-and-butter for most screen printers will be one and two-color work for local business, clubs, schools and anyone else who buys and wears T-shirts. What you will see in busy shops will be multiple jobs set up on a single press at any given time. With a six-color press, you have the potential of setting up six one-color jobs and have them ready to go when the work day starts.

The platen is the board where you position the shirt for printing. Often you will hear people call the platen a pallet, but the purist will argue that the proper term is platen. Some presses, even multiple color presses have only one platen for printing. More commonly, you will see multiple platens, usually the same number of platens to match the number of print heads on a press. These platens will move around the press independently from the movement of the screens around the press.

Platens move for two reasons. The first reason is to print a white underbase on a dark shirt, rotate the platen under a flash cure unit, and then back to print the others colors on top of the white underbase. We ideally need our platen to move so that we can properly and efficiently print dark T-shirts. Can I print dark shirts with a single, non-moving platen? Yes, but I will have to move the flash unit over the platen each time. It’s all a matter of efficiency.

The second reason platens move is so we can have someone else loading and unloading shirts while we print. A helper loading and unloading will speed up the process. During day-to-day printing though, most manual presses have a single operator, and automatic presses will commonly have two operators, a loader and an unloader.

I get the question often about purchasing an all-heads-down press. That means you can print any screen on any platen, all at the same time. If your press is not an all-heads-down machine, you can only get one screen to lock down in place on one platen at a time. The only time I’ve ever had need of an all-heads-down machine has been in a classroom setting where a large number of students are attempting to print sample garments. In nearly all shops, only one operator is on a manual press at any give time, so all-heads-down is an added expense that most of us would never use. So, unless you’re opening a screen printing school, you can save your money. Some manufacturers have ceased building all-heads-down manual presses due to lack of interest in the marketplace. Of course, automatic presses are all-heads-down devices, as all screens print simultaneously.

Setting up the Press
Loading a screen on the press is a simple operation for a single color. Each additional color in the job complicates the process exponentially. No matter how many colors/screens in the job, we want to lay out our artwork in the center of the screen (from side to side) and slightly higher on the screen (from bottom to top). This positioning allows for ease of setting up on the press, and allowing room at the bottom of the screen for a reservoir of ink, and room at the top for clearing the print area with the squeegee.

The screen will lock into place in the same place each time on our platen. If the artwork on our screen is square with the platen, then it goes to reason that if our shirt is placed on the platen straight, our print will be straight on the finished garment, print after print.

Each screen is held in place by either back clamps (across the bottom end of the screen), or side clamps (on each side of the screen). Once locked down, the screen should not move and will fall in the same place each time you lower it onto the shirt and platen.

Setup the screen so there is about 1/8” clearance between screen and platen. This is called printing “off contact”. The only place the screen will physically touch the shirt will be along the sharp edge of the squeegee blades as it passes across the surface of the screen. Printing off contact will give us a clean, crisp print on the garment.