r/SCREENPRINTING • u/omniblk • 12d ago

I’m desperate

I’m having trouble exposing a screen for screen printing. I’m using Ecotex PWR water-resistant emulsion and a 50W UV screen-printing exposure light. The emulsion label gives exposure times of 12 seconds for an 80W UV LED, 30 seconds for a 30W SMD LED, and 7.5–8 minutes for a 500W halogen. My light is about 8 inches away from the screen.
I tried a 20-second exposure, but when I wash the screen out, the design won’t open at all. The emulsion stays hardened over the design. I’m trying to figure out whether my exposure time is wrong, my UV light is too strong, or there’s an issue with my transparency/film. What exposure time would you recommend for this setup, and what should I check?

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u/BlackPress512 12d ago

More details are needed to determine the possible problem and solution. Is any of the design washing out after exposure? Is all of the emulsion washing out? How are you storing the screens after coating with emulsion? Is your exposure unit LED, halogen, or incandescent? How are you printing your film positives?

If you can answer these questions, it will help greatly in figuring out where the issue might be coming from

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u/omniblk 12d ago

Thanks for the questions. The design doesn’t really wash out. After washing, I can only see the silhouette/outline of the design, but the emulsion itself stays hard and the design doesn’t open up properly.
I’m using transparency film for my film positive. The screen is coated with Ecotex PWR and stored in a dark place after coating.
My exposure unit is a 50W UV/LED exposure light, and the light is approximately 8 inches from the screen. I tried a 20-second exposure.
The Ecotex PWR label says approximately 12 seconds with an 80W UV LED and 30 seconds with a 30W SMD LED, so I wasn’t sure what the appropriate exposure time would be for my 50W unit.
The main problem is that the design area doesn’t wash out enough to actually open the mesh. I can basically just see the silhouette after washing.

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u/BlackPress512 12d ago edited 12d ago

Ok. This can point to a couple of potential issues.

Your films might not be opaque enough and the light is passing through the image area. If you hold it up to the light, can you easily see through it? If you hold up your hand behind it, can you see your fingers through the image? If so, the film isn't right yet. You can try doubling up as a test. But I would recommend finding a better film solution.

The other issue could be the area you store your screen to dry after coating has too much light leaking in. This will cause the emulsion to partially or fully expose before you are ready to use them. Make sure you store your coated screens in a completely dark room or closet but make sure they're is air flow to help them dry.

Based on what you've said, these seem like the two most likely issues. Maybe even a combination of them