ONE COAT OR
TWO?

What a coat actually is

In a fluoropolymer system a “coat” is a complete application and cure cycle, not a second pass with the same gun. A one-coat system puts a single engineered film onto a prepared substrate. A two-coat system applies a primer formulated for adhesion to the metal, cures it, then applies a topcoat formulated for the surface properties the part needs in service.

The division of labour is the point: the primer's job is to stay attached to the substrate, and the topcoat's job is to be slippery, chemically resistant or wear resistant. One film asked to do both does each of them less well.

When one coat is the right answer

• High-volume production — fewer cycles, lower cost per part. The 958G-313 system named on our coatings page is the industry standard here.
• Moderate service conditions — where the load, temperature and chemical exposure sit comfortably inside what a single film handles.
• Thin-film requirements — when the drawing's dimensional tolerance will not accommodate a two-coat build.
• Cosmetic and release work — where the requirement is a clean non-stick surface rather than survival.

When two coats earn the extra cycle

• Difficult substrates — where adhesion is the limiting factor and a dedicated primer is the only way to get the film to stay put.
• Aggressive chemical service — a topcoat chosen purely for chemical resistance, with the primer handling the bond.
• Longer required service life — more total film to wear through before the substrate is exposed.
• Higher temperature or thermal cycling — where differential expansion between coating and substrate would defeat a single film.
• Customer specification — some prints simply call for a two-coat build, and that is the end of the discussion.

How to specify it without guessing

You do not need to pick the build yourself. Tell us the substrate, the service temperature, what the coated surface contacts, the contact pressure and which dimensions are critical, and the system follows from that. If the surfaces around the coating have to stay bare, that is a hard masking question we will raise at the same time.

Our coating selector covers this in four questions, and a free sample run of up to 10 parts will settle it on your own components. For the underlying resin choice, the Teflon™ coating page covers PTFE, PFA, FEP and ETFE.

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