Shape of acetate paper appearing on screen

[Meshie]

Hi there,

I have a little problem after exposing my screen. When I wash out the image the shape of the acetate paper also appears, so I end up with a faint box around my artwork. What would be causing this?

Thanks.

[Shamax]

Heya Meshie, welcome to the forums!

When you say the shape of the paper appears, do you mean that it washes out to the point that ink would pass through it, or do you mean you can just see a slight discoloration in the emulsion? The latter happens pretty regularly and won't affect your print. It just means that the blank portions of the transparency itself blocked a *little* bit of the UV and changed the color of the emulsion. If it's the former, though, and it completely washes out the emulsion in those parts, then you've got an underexposure problem. In that case, you would probably need to let it expose for a little bit longer to keep the edges from washing out.

Just remember that a slight difference in the color of the emulsion is normal (at least, it is for me) and won't affect the quality of our print. If you've got further questions or info on this issue, we're all here to help!

[Meshie]

Yeah that's what I meant. Discoloration in the emulsion shaped like a rectangle(acetate sheet). I've just ran into another problem. I seem to be having some trouble removing the emulsion from the screen. It hasn't been over exposed. I exposed the screen for less time and the emulsion will not remove after using the decoating chemical. I then tried the Haze remover. That did nothing. I'm not sure why this has happened. Decoating the screen worked fine last week. Is there anything else I could use to remove the emulsion? Thanks for your help

[ApeShirt]

Are you using a pressure washer? If not, I recommend trying that first. That is what most use. A good emulsion remover and a pressure washer should do the trick. Is your emulsion old? That could be the culprit of your exposure problems.

[Catspit Productions]

The slight discoloration in a rectangular shape is due to a minimal under exposure. I’m guessing your film positive is cloudy or very hazy perhaps like vellum. That causes a slight underexposure at times since the vellum prevents some of the UV light form penetrating through to the emulsion. As long as this does not cause pinholes or anything like that it is perfectly fine and normal as Andy suggested. The clearer your film positives are the less that will occur.

As for your reclaiming process, Greg is correct in suggesting a pressure washer. You’ll need one to reclaim screens easily. If you are using a pressure washer and it still won’t reclaim you may have what we call screen lock. Some chemical or even ink can be absorbed into under exposed screens and cause the emulsion to cross link or “cure.”

Like Greg said, a pressure washer and a decent emulsion remover is your best bet to reclaim any screen.

[Meshie]

Hey people, thanks for your comments. I did a little search online and found out that a small amount of bleach removes emulsion from a locked screen. I used this method after trying all other options. It worked very well, although the information did say that bleach will ruin the mesh if used too much. I'll have to use this method with caution