Most screenmakers are surprised to learn that there are no safe lights for screenrooms that are devoid of UV energy. The truth is that all lights, whether the common yellow bug lights or “safe lights” that are covered with UV filter tubes over florescent tubes and sold as “safe lights” will have a safe handling time before the emulsion starts the cross-hardening process.
The longer the coated, but unexposed screens stay in the darkroom they become prematurely hardened, and the longer the exposure will be.
And, not only is the premature cross hardening costing you in terms of exposure time, it is preventing you from achieving the maximum resolution possible in your stencils. You do want to hold those small details in your stencil and have them print, right?
Safelight “handling time” varies with the sensitivity of the photographic emulsions and their relative distance from the lamps. Normally a safe handling time is approximately 15 minutes duration for screenprinting emulsions. That is the total amount of time that unexposed emulsion could remain in the light without some increase in exposure time or loss of resolution. You cannot expect to place unexposed emulsion on screens in an open shelf system and leave the lights on continuously throughout the day.
You don’t know what you don’t know. Invest in learning what you don’t know in order to fix the unknown problems. Don’t assume that you do not have a problem if you do not measure the situation.
Simply print it out and follow the written directions to find out how much time you can save and how much resolution you can gain. It is important.
Format: PDF File
File Size: 384 KB
Print Length: 1 pages
Publisher: Solutions Publishing
Sold by: ScreenprintBooks.com
Author: Bill Hood
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