I don't know what's up. I needed to burn two images for band tshirts. One worked, the other didn't (and hasn't the additional two times I tried). Same preparation + burning process. Why would one work and not the other? Both images printed black on transparency, both burned for the 20 minutes I typically use (500 watt halogen bulb), but one wouldn't wash out. Any suggestions? Any chance the transparency image could somehow not be dark enough? It looks black, is black, but maybe not super-duper black?
What emulsion are you using? 20 minutes is pretty long, even for a 500W halogen.
Did you print both the positives with the same settings? Should use heavyweight matte or similar setting to lay as much ink as possible.
Are both transparencies the same?
Does the one that doesnt work have more fine lines than the other?
hmmm... not sure of the emulsion. I transferred it to a cleaned ketchup bottle a while back for easier application.
The 500 watt halogen is placed about 2 feet from the screen; maybe a little less.
Both images were created in photoshop... transparencies look similar in tone (different images).
The one that doesn't work actually has fewer fine lines--the non-working one is text; the other is a line-filled image of trees.
weird, really. I can't figure out what's going on.
The screens are over exposed; either a positive that is not dense enough or too long an exposure time. 20 minutes does sound too long. Have you burned other screens previous to this job that washed out ok using the same setup? - Scotty
-Double your transparancies if you don't already to create a darker image. Perhaps even use three transparencies depending on your printer.
-Play with your exposure time. Overexposing can be the same if not worse than underexposing. You must really test out for perfect exposer times based on your setup. This will change based on your stencil thickness, type of emulsion, exposure setup and so on.
-Make sure your design is not getting exposed between your light source and washout boothe / method. Simply fix this by putting your screen in a black garbage bag when transporting it from room to room or under any kind of light.
-Do you have a sheet of glass on top of your screen to make sure that your transparancy is laying flat on your screen and no light is seeping beneath?
Try to pinpoint what went wrong between the two screens for you, and where to start fixing your problems since there are so many variables that can effect your exposure.
frustrated with exposure, please help 
