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Exterior Coatings and Finishes

What are the different types?

There are at least 6 categories of exterior coatings: silicone polyester, silicone enamel, sol-gel ceramic, porcelain enamel, enamel on steel, and high temp exteriors/high temp paints.

  • Silicone Polyester coatings are made from silicone polyester resins, which contain a copolymer (a silicone-modified polyester resin). If formulated properly, these copolymers may exhibit the best characteristics of both the silicone and polyester components. These exterior coatings have good temperature resistance, good durability, with good resistance to normal wear and scratching.
    In general, coatings can be applied to any normal cookware surface: rolled aluminum, cast aluminum, anodized aluminum and stainless steel. Stainless steel may require additional roughening to promote good adhesion.

  • Silicone enamel is simply a pure silicone coating (without the polyester).
    Sometimes people confuse a silicone coating or enamel with a silicone polyester coating. They will ask for a silicone coating when they mean a silicone polyester. Also, beware of the term enamel; it is a very general term and can mean something different to all that use it.
    Differences between a silicone polyester and true silicone coating would be that a pure silicone, as a positive, has better temperature resistance and hot hardness; the downside is that it is much more brittle (and can chip more easily). Generally adhesion is more difficult to obtain (a pure silicone in most cases will need a grit blast to get decent adhesion versus a silicone polyester which can easily go on an etched or cleaned aluminum surface).

  • Sol-gel Ceramic coatings come in between silicone polyesters and porcelain enamel, as they offer a blend of both worlds. They offer high hardness and high heat resistance like porcelain, but the application is as simple as that of silicone polyesters, therefore, offering a cost savings over porcelain. They also offer better chemical resistance, over porcelain enamel coatings.

  • Porcelain enamel on aluminium coatings are very high-temperature coatings, made from a frit (similar to high- temperature ground glass). Porcelain enamel coatings start out as a frit, which is a glass-like substance. For some substrates, such as aluminum, there are special formulations. The cookware factory grinds the frit with pigments, water and additives in the ball mill to make a slurry. The slurry is then sprayed onto the pan like a liquid coating. It is then cured at around 550C.

  • Porcelain Enamel on steel is only slightly different in that the parts are dipped instead of sprayed (enamel inside and out) and cure is around 820C to 850C.

  • High temp exteriors / high-temperature paints: Can be all of the above from silicone polyester to silicone to porcelain enamel - this would be a generic term used to cover most exteriors.

Coatings that contain PTFE are usually more expensive and not suitable for exterior coatings, unless trimmed from the bottom. PTFE also degrades quickly when exposed to direct flame or heat source.

 

 
 
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