[a sparkly pony]

Hello everyone! I read through several posts to see if I could find this exact question, but I wasn't quite sure if people were asking the same thing. I have just started screen printing at home, and have successfully exposed about 4 screens. I have a home made light box and am using screen printing superstore brand emulsion. Exposing for 4 minutes has worked great for me, but today when I exposed my screen only a tiny bit of emulsion came out of the exposed image. I can see the yellow shape of my art clearly on the blue-green emulsion, but no matter how much I spray nothing comes off. I am going to try again. I have never had this happen and have had at least 4 successes following the same formula. I am ordering some new emulsion as I have had it mixed for about 4 weeks.
Anyway, excited to have found this forum and look forward to learning more! Thanks in advance.

update! I compared the bad screen to a good screen, and it appears as though I was much lighter with the emulsion on the bad screen than on the good screen. The areas on the bad screen that sprayed out were where the emulsion was thicker... could this be the problem?

 

[n.signia]

Make sure your transparency is all the way against the emulsion, if its not flat and touching, light will get around it, exposing the emulsion enough that you will not be able to wash it out, but will still see where the image would be on the screen.

 

[PositiveDave]

You could be partially cross-linking your screen prior to exposing? Are you working in safe or subdued lighting?
Could be light getting through your mask, (put a coin on the screen and see if it washes out). Thin areas would be disproportionately affected.
Could be your emulsion has gone off?
If it's undercutting, the edges would be affected rather than the centres of blocks, is there a difference?

 

[RespecttheCraft]

definitely have a piece of glass on top of your transparencies to prevent undercutting and make sure your working and storing unexposed screens in safe light (you can buy a yellow bug light from a grocery store)

also, use a pressure washer. i dont even turn mine on; just let the water come through the nozzle and its enough pressure to wash out the design. also, its helpful to spray water on the screen and let it soak wet for a few minutes before you begin trying to wash it out. helps to soften the dried emulsion

 

[PositiveDave]

Beware uv treated glass, it may reduce your uv light.

 

[Celtic]

Also, make sure that your emulsion is completely dry before you expose it.
And, when you get a yellow bug light, be sure that isn't a fluorescent one....that won't work.
You want an incandesant bulb.

 

[PositiveDave]

Also, make sure that your emulsion is completely dry before you expose it.
And, when you get a yellow bug light, be sure that isn't a fluorescent one....that won't work.
You want an incandesant bulb.

A fluorescent light is fine with a yellow filter. I worked in R&D for many years under them.