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"Shiny Film" on Screens within Stencil

1673 Views 6 Replies 6 Participants Last post by  jsf

I am pretty new to screen printing and have only made about 10 screens so far for our clothing company. It seems after burning the screen and then washing out the emulsion, there is always a "shiny film", almost like an oil slick, within the stencil design. It doesn't cover the whole design, only certain areas.

For instance I can hold the screen up to the light and in some areas of the design, the screen is completely clear and see-through, and in others the shiny film seems to block and almost clog the mesh.

Could this be due to underexposure? When washing out I use the garden hose with a jet stream sprayer. The image always washes out nice and crisp, but the shiny film persists.

I'm wondering how to get rid of this and if this could be a cause for the thin layers of ink and splotchiness I get sometimes while pressing?

Any help would be extremely helpful.

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does the film go away after the screen dries or is it still there after the screen is dry?

Still there after the screen dries. Now I was just working on some prints a couple hours ago and using a screen that had the film/residue in the screen. However, after washing the screen really well with screen wash and blasting it with water at a close range, I noticed the film-residue seems to be completely gone.

Any ideas on what's going on now?
spit on your finger and rub it out. from both sides at the same time. works for me. don't have a clue what it is. randomly happens to me sometimes.
It's probably emulsion residue which is drying in your stencil. After washing out your screen, water droplets on the squeegee side of your screen picks up uncured emusion and settles in your stencil. As it dries, it leaves a thin film, preventing ink from passing through.

After washing out your screen, run your finger on the squeegee side of the screen. If it's slimy, that means it's not fully cured. You need to increase your exposure time. I had the same problem, however when I tried inceasing the exposure time, I had a difficult time washing out my design. I had to resort to using an air compressor to blow out any water in and around my stencil. I have since made my own exposure unit with a 1000 watt metal halide bulb. That has taken care of the problem. Now I get clean clean washouts, with no slimy residue on the backside, no residue in my stencil.

Hope this helps.
spit on your finger and rub it out. from both sides at the same time. works for me. don't have a clue what it is. randomly happens to me sometimes.
Exactly what I do, strange huh?
Yup, that is emulsion residue or slime that dried. It can be cleaned by just washing it again with water. I do it sometimes with foam and detergent. :)
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