Screen Degreasing: Pinholes are the Enemy!

by | | 0 comment(s)
Degreasing a screen with Terry Combs

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.

This entry was posted in no categories.

You must be logged in to post comments.