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Old 01-28-2006, 10:42 PM
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Hey Barry, Hey Martin 15 degree rule

You always see someone asking a question or making a comment about temperture and how it affects painting. One guy did a "test" with the quality of mud over epoxy. He had mentioned that he heated the epoxy to speed up its dry time. Since that thread I've been thinking,at a recertification a couple of years ago I remember them talking about the "15 degree rule". For every 15 degrees over 70( because 70 is the temp that all p-sheets are set up on as far as PPG goes) you cut the flash time or dry time in half. For instance,if a products flashes off in 15 minutes@70 degrees then it will in turn flash off in 7 minutes@85 degrees. Is this true for all paint lines? if the guy heated up the epoxy to speed up flash and then put mud on it that heats up as it dries I would say that the window ran out on the epoxy. Most people who use epoxy under mud my not realize how hot drying mud is and what it can do to flash time.
Now I'm not picking on that guy I just want to make sure that the "do it yourselfer" understands this rule. In the summer inside my paintbooth( I do collision painting) I have to almost go back to back coats from sealer to clear because of the heat and humidity and the "15 degree rule". I just want to be sure others know this. Going past a flash time can cause you great pain depending on what you use.
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