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Originally Posted by overthecurve |  | | | | | | | | | I expose my screen for around 1 hour with a 150 halogen watt light. And i started to hose it outside (was dark and used a light to see what i was doing) it was starting to work and then it just wouldng come out. After trying it for about 5-7 min i gave up and then i was washing it off with just warm water since i didnt get my remover yet, then the mould was starting to show but then just went away for good.
How long should my expose time be with a 150 halogen light.
The height is about 17inch away from the screen.. | |  | |  | |
If the stencil doesn't wash out, it was crosslinked somehow - either UV light, stray light in your shop or too much heat (110F+) for several days.
Your positive may have failed and light got through it. Next time you expose, tape a dime to an unused area of the stencil as a proof. No light will penetrate the dime and it should wash out like a dream. If your image area doesn't wash out the same way, your positive is weak.
You can do better than 150 watt halogen lamps even on a small budget. Big box hardware stores have 500 and 1000 watt quartz halogen work lights, but they get very hot - watch out. Remember, even though you may be putting 500 waats into the lamp, most of it is generating heat and white light for reading or working - NOT UV. UV is just a handy byproduct for us.
Remember to remove the protective glass. It's there to stop UV light from damaging your eyes.
Learn to make a step test to determine exposure time.
http://www.ulano.com/video/UlanoExposureTest.256k.wmv
Use a fast exposing SBQ emulsion to compensate for your low UV light source.
expose time 
