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| Posted on 5/24/06 at 12:13 PM | |
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The change in seasons is a popular time for stencil problems if you don't have a screen room that is a controlled environment. Different humidity and temperatures play havoc with exposure time. Screen_Guy is right on target with his suggestions, and UNDERexposure is the #1 cause of problems in screen making. You don't mention your exposure equipment or the actual emulsion you are using, but this is the Ulano board. SBQ emulsions are particularly sensitive to strong solvents when they are under exposed. The solvent fuses the polymers that are not crosslinked with UV light. This is a bond that stencil removers can't break. Stencil removers can only break up a properly exposed stencil. The KIWO Pregasol you used is an excellent stencil remover that comes in Ready To Use, or a 20:1 Concentrated version. I don't want you to use bleach. Bleach is slower, more damaging to the environment, smells and, most importantly, considerably less reliable than commercial stencil removers because the concentration must be exact for it too work and it varies from emulsion to emulsion. Here is a test. Coat a small area of your screen. Tape a positive to the stencil. Tape a dime to the stencil and take it out in direct sunlight for 2 minutes, which is about the equal to 4 minutes of an 8K Olec lamp. The dime is the ultimate UV blocker. Your positive may be failing your by not stopping enough UV light. Watch how it washes out and then remove it with a proper stencil remover. It should reclaim without anything more than water pressure. Maybe at the edges it needs more pressure, but that's why pressure washers are so popular. ____________________ Richard Greaves, ASPT Ulano Corp. New York Technical Services 718-943-1338 direct | |
  
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