Screen Printing Forum

hi everyone! nice to meet you.....
i am having a problem. for the last 2 years i have been making my screens by printing the image onto regular computer paper, rubbing canola oil on the paper to make the paper transluscent ( a weird habit i picked up ) drying the paper and burning the screen in the sun. i have never had a problem woth this method.
recently i bought an exposure unit. i used my oil paper method and followed the instructions. the screen washed out beautifully and i laid it in the sun to harden futher.
after printing 10 shirts, with waterbased ink, i needed to wash the screen, as i washed the screen the emulsion started coming off. what happened?? after it hardening in the sun i thought it would be set.

oh yeah and i bought some transparency film to try again, but i am just curious to know what you all think.

Having a little trouble getting the timing right with my light box right now brings me to wonder about this exposing in the sun method. . . How do you achieve any kind of consistency? and/or what are the secrets of this trade. . how long, time of day, temp., idk, this just doesn't seem like it could work, but it is not at all the first time I have heard of it.

Bungaloe what kind of emulsion are you using?

As for the sun, every lamp is a replica. I haven't done it in a while, but here in Sunny Florida in August using ulano rlx it takes 3 minutes to expose, in the winter 4 because the source (sun) is further away from the earth, kinda like moving your light source closer to screen during exposing will affect exposure time. I haven't done it in a while because I no longer expose 8 and 12 foot frames since I went with a large format solvent printer a few years back. When I did I usually used black vinyl cut reverse and stuck to screen for art as the things we did that large were fairly simple. Now I can put photos on 4x8's all day no problem. There are quicker exposing emulsions than rlx if you want to go for it and try halftones or complex stuff with the sun and film on t-shirts, it'll take some experimenting to get it down and then when you're relying on it for jobs it will rain for a month.

Water based ink tends to eat at emulsion more than traditional plastisol ink. On large print runs I will make two screens for each color so if this does happen I switch them out and have no downtime. usually this is only the case on shirt runs over 800 prints. Also make sure your using a good emulsion. Cheaper is not always better. Hope this helps!