A: We are getting different results in gloss value using my electric oven vs. the gas-fired oven of my customer. The gas-fired oven gets lower gloss than our electric oven. The metal temperature of the parts is the same (185°C) in each oven, and we have verified this with an Easy Track Oven Profiler temperature recorder.
The product is a semi-gloss hybrid powder with a target gloss of 35-40%. Could there be an effect on gloss from the fumes of the gas-fired oven? My only knowledge is that using a gas-fired oven can result in yellowing. But does a gas-fired oven also produce variations in gloss vs. an electric oven?
A: Gas oven environments can be highly variable depending on the quality and consistency of the incoming gas and also the quality and consistency of the combustion in the burner. Furthermore, the amount of exhaust set in your oven can affect the quality of the powder-coated finish.
Qualifying the effect of the gas-fired oven environment can be accomplished by isolating the powder from the oven environment while still allowing it the same bake. This can be done by powder coating one test panel and placing it in a closed tin can. Puncture three or four small exhaust holes at the top side of the can to allow for escape of volatiles. Powder coat another test panel and hang it outside the tin can and place the can into the oven.
After stoving both panels, examine the color, gloss, and appearance of each finish. If the gas environment is excessively altering the coating, the effects should be very obvious. You can “map” an oven by placing multiple panel-containing tin cans in various locations in your oven.