So, I've tried a handful of halftone prints, all came out pretty well. When i reclaim my screen I can get most of the emulsion washed out easily except for a couple little halftone dots....is my screen underexposed? or do I just need a pressure washer? or both?
Oh, I'm printing on 230 mesh yellow screens. 2min 50sec exposure time over two 48" unfiltered blacklights (about 12" below)
what is the best way to remove ink stains from your screens?
Lay your screens on a bed of thick paper towel soaked in bleach. Put more paper towels soaked in bleach on top of it and cover it with some plastic sheeting. Lay some heavy books on top of the plastic sheeting making even contact across the screen. Let it sit overnight then wash. Most of your emulsion should dissolve right out. The more airtight you make the package the better it works.
Underexposed emulsion sucks, it's really hard to remove in spots where there's already some ghosting.
Pressure washer is key -- especially with water resistant emulsions -- but I sometimes end up with spots that don't fully wash out, even with the stream on the tightest setting. Haven't used dehazer, I guess I should start, huh?
It is very important to never let the stencil remover dry. It locks the stencil in the mesh with a permanent chemical bond.
Under exposed stencils are harder to remove than completely cured/exposed stencils.
Under exposed means some of the sensitizer did not cross link. This is always on the inside of the stencil because invisible UV energy didn't have enough time to move all the way through the stencil to the inside. Penetration of UV energy is not 'linear'. The deeper the UV energy has to penetrate, the longer it takes based on the physics rule called the Inverse Square Law. If you double a distance energy has to travel, it takes 4 times the energy - NOT double. Many low energy UV lamps may never penetrate a thick stencil.
When you spray stencil remover on the stencil, it has to penetrate and attack the chemical crosslinks formed by UV exposure. No crosslinks - no easy stencil removal.
The stencil remover chemical creates another reaction with under-exposed stencil and forms a chemical bond with the mesh that is very difficult to remove.
Always get a pressure washer, it'll solve every issue with reclaiming. Also make sure your reclaiming chemical isn't drying on the screens before washing out, this will damn your screens pressure washer or not. I use Pregasol coat it, and wash it out straight away, then de-grease and de-haze.
Ok, Finally was able to borrow a pressure washer. worked perfectly and got all the little bits of dried emulsion out.
Also tried out some of the "the green stuff" dehazer/degreaser. works awesome. highly recommend it.