Well I have been doing a lot of trial and error with my new (to me) Printa 770 Exposure unit and still not having much luck.
Im not positive of the wattage but its a blacklight UV unit. Printa doesnt seem to post their users manual online and they are hard to get on the phone as well.

First I was trying to burn my screens with something I traced in opaque paint marker on vellum. 10 tries with varying times and kept seeming like it was over exposed.

Now Im doing my trial and error with transparency film positives. They are super black/opaque and I even have them double layered just in case.

I started with 2 minutes and it STILL seemed over exposed, is it possible that I may need an even lower exposure time? I was able to wash out the larger areas of the screen but the fine details would not wash out..
Any advise is greatly appreciated.

THanks@

Cannon

Yes, certainly. An over exposure will "choke" the fine lines and details and start to cure the emulsion through the film positive. Try lessening the exposure time by 15 to 30 seconds and see how it washes out.

Did you ever find success with the 770 @gamehendge02. I am about to work with the 770 and wondered if you have found the sweet-spot for it? Also what emulsion have you been using?

You'll probably have to reply to a thread for that contributor or send a PM.