Prepping Your Screens for Press Setup

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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.

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