Screen Printing Forum

sorry for all the questions, heres a last ditch effort to finish a project before Christmas,

I originally planned for using a modified work light to expose my screens, the screens are halftoned, i have to realize that wont work.
HOW ABOUT THIS: buying a 150 watt high pressure sodium light and modifying it so UV rays are released, would this cut the cheese?
thank you for your time,
-Running out of time

i use a halogen shop light, works fine.

just do some test exposures to figure out a good distance and time.

try something like this...

You'll have the best result by choosing a light source that emits the highest amount of UV rays between 440 and 660 nanometers. Some lamp manufacturers will provide you with a spectral analysis of the output of their lamps. Unfortunately, halogen is very low in this UV range, but will expose screens given enough time (so will tungsten light bulbs after a few days). Sodium vapour generally, provides higher output in the preferred UV range, but typically will also put out a lot of IR (heat). If you can vent the heat to keep your stencil from getting too hot, you should have a winner! (Heat will cause the sensitizer to cross link or harden)

I agree with "ivescreened..." in that an exposure test of some kind is a necessity, especially prior to imaging halftone stencils. Try to make sure that your test screens are coated exactly the same in the scoop coat method, mesh count & colour, time and distance as you plan for your image stencil. Also try to replicate the drying method used after coating as well as the temperature.

Good Luck & Merry Christmas!
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