This is my first post and I'm looking for a little advice. I'm exposing and printing on a basement rig that I fashioned and my first project went great. Little to no issues at all. We got the exposure time dialed in and the stencils are washing out great. I just burned my screens for another print and the edges are coming out hazy and I can't figure out the issue. The screen almost has a wet appearance just insided the stencil even though they dried overnight. Check out the photo and if you have any suggestions they would be appreciated.
looks like some emulsion was still in the stencil. if it hasnt been under sunlight it should continue to wash out. you need to really rinse your screens well and sometimes let them dry flat to avoid emulsion water seeping into the stencil. regardless, a good thorough rinse should help remedy the situation.
If you look at your dried stencil at an angle to the light, you can usually see that shit. It's a bit reflective.
If you get to it before it has had time to cure into your stencil you can usually get it out by wiping down the down (exposure) side of your screen with a soaked rag.
Of course it's best to avoid it in the first place, and you do that with a even, thin coat, a good burn, and a thorough washout, as others have said.
Yeah, this exact same thing happened to me to some degree for the first 6 months of printing. I was always scared to over-wash my screens cause I worried that the hardened emulsion would rinse out. A few weeks ago after looking around the boards I washed the hell out of my screen, dried it horizontally as Andy suggested, and my screen turned out perfect. I wish I had figured this out earlier. That's part of the beauty of screen printing though for me, almost every print results in finding out some new solution that makes the process a little easier.
If you think you are done your washout, run your finger over the surface. If it is sticky or some emulsion comes off, you have not completed your washout. And you have to wash the whole screens - just washing the image area will leave soft unexposed emulsion on the surface in the non-image areas, which will drip back into open areas, especially if you dry them standing up.
If you lay some newsprint on the washed screen, if it picks up any colour, the screen is not completely washed or underexposed, or both.
if the stencil falls off after a good wash, you are under exposed.
A well exposed screen will allow you to wash as long as you need to without affecting it.
A good exposure leaves (a) a 'hard' (not sticky) top surface, and (b) all your detail contained on the film.
If this is not what's happening, then there are other things to check/change.
The way I do it: After exposing, washing out, then wiping the screen down using a paper towel, I use a compressor w/an air gun attachment to blow out the rest of the water that's in the screen. Most printers I know do this. If you don't have a compressor, just take the paper towel you used to wipe the excess water off, and lightly tap it on the image area of the print side of your screen. It takes a minute, but tapping it like this should open up whatever water was left behind by the final wipe. Then do as Andy said and lay horizontally to dry..
Sometimes a little bit of water dries in the screen anyway. It will block the image, as you already found out. Like crosshair mentioned, you can see this when u hold it to the light at an angle. Even if you wait too long, and it dries in the screen, I've found using a little spit gets it right out. Spit on your finger (that's what she said), then rub it into the spot on the print (exposure) side until it clears up. Works like a charm! Also, if you don't notice it 'til after you've started printing, no worries, just clean the screen of any ink and spit away..