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Discussion Starter · #1 ·
I am trying to expose a 280 mesh screen. The design has pretty large amount of fine details. This is to be printed on recycled card stock.

I made two passes while coating the screen, so doubled on both sides. I exposed it using a flood light from ryonet. I exposed it for 20 minutes. I tripled my positives.

When washing it out, I found that some of the finer detail parts would not wash out fully (I am using a garden hose to wash it out set to jet spray). I tried to put the nozzle up real close to wash those bits out, but ended up washing out the middles of "e" and "A" ect.

After being at it for some time, the emulsion stared to peel around some of the edges and have a lighter color around most of the edges.

I dried it with some news papers, there was no excess sliminess to the emulsion, nothing came up with the paper.

After cursing the gods, I reclaimed the screen. The emulsion washed out really nicely. I've never had a screen be reclaimed so easily before.

Is this an exposure problem? Too long? Too short? Having under the hose for too long.

Thanks, help! (I need some body)

174 Posts
Get a film that is dense enough to only need one.

Do a step wedge test to determine your necessary exposure time. An exposure calculator strip would be better.

You under exposed your screen. Guess work leads to frustration. What is you time worth? Document and measure what your setup does and find the necessary exposure time.

A search on this forum will provide you with answers...


keywords... step wedge test

1,810 Posts
Exposure problem

Your obsession needs to be the white whale of the sharp, opaque positive.

You don't tell us how you made your positives, but every extra piece of paper or film makes the exposure longer.

Laser printers are notoriously poor at stopping UV energy. Try feeding the same piece 3 times. It is very hard to line up fine lines with 3 positives. Your equipment is probably not good enough to print those fine lines.

Flood Lamp?
Any lamp with a filament has very little invisible UV energy. Are you sure Ryonet sold you a flood lamp? Perhaps you meant a quartz halogen lamp? Still, only about 1% - 2% UV output, if that.

Mesh thickness and color, stencil speed and vacuum are variables that effect exposure.

Start measuring your stencil hardness with a Stouffer 21 Step Sensitivity Guide.


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