Letter 31081

Pretreatment oven oxidizes copper parts, then epoxy won't adhere [So. Carolina] 

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Recently we installed a new oven to preheat copper parts prior to coating with epoxy insulation. Typically we run the oven about 330 degrees F, and the parts are in the oven for 21-25 minutes. Since the installation of the new oven, we occassionally see a silver patina coat the bar during pre-heating, and this causes adhesion failure. When the cured epoxy insulation is pulled off, the silver color is evident on the backside of the insulation.

The entry and exit doors to the oven open every 7.5 min for approximately 30 seconds for parts to convey in and out. The oven interior is approximately 230 cy in volume. We have discussed introduction of an inert gas to the combustion process, but feel this would be ineffective and costly on an oven that is opened so frequently.

Elliott Phillips
Epoxy Coating - Greenwood, SC, USA

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