we have run into an issue recently where after washing out the screen following exposure the stencil looks good (even with some small, 10 pt type) but there are a lot of ~tiny~ pinholes in the screen (you can only really see them when you hold the screen up to light). when we print through the screen, there is definitely ink passing through these problem areas when any sort of real pressure is applied to the squeegee. we think we have narrowed it down to the screen being slightly underexposed, but i was wondering if anyone knew of anything else that might be causing this??
we are using 200 mesh screens and Ulano TZ water-resistant emulsion with oiled positives and an overhead exposure unit.
thanks for any advice,