bzztbomb
Ulano TZ/CL Emulsion test
I switched emulsions recently because this stuff is supposed to be clear which should make multi-layer screenprinting easier. But new emulsion could require a new process, so I made this test screen to figure out how long to burn it for.
I ordered a freakin' gallon of this stuff. I don't quite do enough screenprinting to warrant mixing a whole gallon if it's only going to last 6 months refrigerated. So I figured out the proportions and mixed about a cups worth.
2 tablespoons (a little less) of sensitizer to 1 cup of emulsion. The actual ratio is 7/4 cups of sensitizer to a gallon of emulsion, which works out to 7/128. Hard to get that without getting fancy, but 2 tablespoons to 1 cup is 8/128 which seemed close enough.
I exposed the screen for 15 minutes with increments of five minutes going down the screen. It's a 150watt clear bulb 18 inches above the screen. I also focus the bulb on the frame of the screen and rotate to avoid burning a harder to clean out spot where the bulb is strongest.
All of the increments worked and washed out fine. If I get really picky, the 30 minute mark seemed like the best spot, there was some weird residue in the 15-25 minute areas, but that may have been purely from being lazy during the washout.
The 30 minute mark seemed like the sweet spot with the Speedball stuff as well, so it looks like I don't have to change my process at all! ;)
Ulano TZ/CL Emulsion test
I switched emulsions recently because this stuff is supposed to be clear which should make multi-layer screenprinting easier. But new emulsion could require a new process, so I made this test screen to figure out how long to burn it for.
I ordered a freakin' gallon of this stuff. I don't quite do enough screenprinting to warrant mixing a whole gallon if it's only going to last 6 months refrigerated. So I figured out the proportions and mixed about a cups worth.
2 tablespoons (a little less) of sensitizer to 1 cup of emulsion. The actual ratio is 7/4 cups of sensitizer to a gallon of emulsion, which works out to 7/128. Hard to get that without getting fancy, but 2 tablespoons to 1 cup is 8/128 which seemed close enough.
I exposed the screen for 15 minutes with increments of five minutes going down the screen. It's a 150watt clear bulb 18 inches above the screen. I also focus the bulb on the frame of the screen and rotate to avoid burning a harder to clean out spot where the bulb is strongest.
All of the increments worked and washed out fine. If I get really picky, the 30 minute mark seemed like the best spot, there was some weird residue in the 15-25 minute areas, but that may have been purely from being lazy during the washout.
The 30 minute mark seemed like the sweet spot with the Speedball stuff as well, so it looks like I don't have to change my process at all! ;)