During 2004, Mi-T-M Corporation started using Hearth Black SSB609H0 on Johnson Gas Fireplaces. They were using a high temperature resistant coating from a competitor but switched to Hearth Black because our product gave them more batch-to-batch consistency in terms of color and gloss. Also, Hearth Black has better transfer efficiency than the competitor's.
The parts that get coated are the faceplates and doors; therefore it is important that the appearance is very uniform and consistent. The fireplace parts see intermittent temperatures of up to 700°F and Johnson has tested the coating to 800°F. However, our technical data sheet reports the extended use temperature to be 500°F.
Hearth Black is applied over hot rolled pickle and oil steel that has been run through a five-stage washer with the iron phosphate stage turned off. After the coating is applied to the parts, they are cured at 425°F metal temperature for about 50 minutes (some parts are ¼ " thick). Mi-T-M has found that the parts must see the full cure cycle because otherwise, the parts can turn out with a higher gloss and darker in color. Running parts back through the cure process will not change the gloss and color. Mi-T-M has also found success in recoating Hearth Black by roughing the surface with a Scotchbrite pad and running back through the washer.
Alesta® Hearth Black provides Mi-T-M a user-friendly powder coating that makes their job easier and provides Johnson Fireplaces that can take the heat!
Courtesy of: Jay Krabbenhoft and Johnson Gas Fireplaces
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