HELP! I'm at my wits end!!!

My guess is that the coated screens were light polluted / damaged with heat (effectively exposing them) between your successful trial and second attempt.

other thoughts:

As other users stated there are lots of variables. Humidity was mentioned. (too much heat will also damage them) Temperature is also a factor when exposing them. I have found it take much more time to expose a cold screen vs. a hot one. The relationship, with my emulsion and exposure unit, of temp and time in the UV is almost linear. That is to say it takes about twice as long at 50 degrees vs. 100.

Are you using laserprinter positives?

You are either under exposing your screen or over exposing it. You should get an emulsion calculator that would tell you your exact exposure time.

There are too many variables to guess at without knowing more information. What kind of stencil are you using? Probably direct emulsion (liquid), do you use a scoop and how many layers are you applying. Also how are you making your image? If its laser on vellum, you may not be getting the density required to stop the light from going through. In addition, how are you getting your light? Is it the same as it was at the start? Ideally you want to look at your process and ask yourself what happened different on the 3rd attempt? If you would like to talk in person, do not hesitate to call. Glenn Doherty, Tiger Graphic Art Supply, 954-907-4574

I've had the same issues. I use inkjet on clear film, i degrease after cleaning, i dry for 2 days, but the dehumidifying this might be my answer. Humm I use my garage to store and work. There is no air conditioner I just run a fan 24/7 do you think that would work for me?

You need to degrease your screen before use, it could give you poor adhesion. It helps to abrade new mesh.
You can calculate exposure by buying a stouffer strip or by this method:
http://www.t-shirtforums.com/t-shirt-articles/t106506.html

I also find that we have that problem when our emulsion gets OLD... It just falls apart.
Try a new tub, and buy it in smaller batches. Also you can try capillary film. Works GREAT for smaller printers... EZ film makes a good one...

Thank God, I don't want to get in that business.

Hello !
I am also a new member. Would a newcomer be warmly welcome here? Good day you guy !

i had nearly the same problems. change your emulsion and try a dehumidifier also spend time to clean and dry screens. haste make waste. and i just started screen printing less than a month