Info on porcelain panels for building exteriors, used in the 1970's & 1980's
Q. I am trying to find out any information (in layman terms) on the factory process used in the 1970's and 1980's to apply porcelain finishes to metal panels designed to be used on the exterior of commercial office buildings. It would be helpful to know what type of primers if any were used on the various substrates. I am compiling a report on various coating systems used on panels for exterior exposure.Andrew Fitzpatrick
- Toronto, Ontario, Canada
A. Enameled steel is typically coated in a two-coat process, using a "ground coat" designed for adhesion to steel, and a top coat designed for color and lack of porosity. Since the enamel has to be fired, primer is not used. The steel may be prepared using a heated power washer, possibly with a phosphate conversion coating.
The enamel can be applied using conventional wet spraying, powder coating, or by an electrodeposition process. It is typical, but not the rule, that the ground coat is fired before application of the topcoat.
Enamel is actually composed of "frit", which is glass and pigments, often mixed with water and binders. The resulting coating is fired glass, which is highly impervious to weather, but brittle enough to flake off if the substrate is bent.Andy Brush
finishing equipment - Strongsville, Ohio
Very concise and informative answer, Andy. Thanks. I see a lot of people calling paints "porcelain" or "ceramic" based on them having particles of ceramic in them, but my understanding, like yours, is that for it to actually be porcelain, the frit has to be fired and fuse together similar to glass.
Ted Mooney, P.E.
Pine Beach, New Jersey
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