Thermal-spray ceramic, thin-film ceramic or high-temperature paint?
Three different products are sold as heat protection for exhausts. Here is what each one actually does.
Three different products
Ask for a "ceramic coating" for an exhaust and you may be offered three quite different things: a thermal-spray ceramic coating, a thin-film ceramic coating or a high-temperature paint. On a finished part they can look alike. They are not interchangeable.
Thermal-spray ceramic
Metal and ceramic powders are melted and sprayed onto a grit-blasted part: first a metal bond layer, then ceramic oxide layers. The result is a hard ceramic layer about 0.3 mm thick, full of fine pores that slow heat down. It belongs to the same family of coatings used in jet engines and gas turbines, and it is what we apply. At 0.3 mm, a coated surface runs about 30% cooler.
Thin-film ceramic coatings
Products such as Cerakote are liquid coatings filled with ceramic particles. They are sprayed like paint and cured in an oven, and the finished layer is very thin, usually well under 0.05 mm. They come in many colours and protect well against corrosion. Because the layer is so thin, they insulate less than a thick ceramic layer.
High-temperature paint
Silicone-based exhaust paint is cheap and easy to apply at home. It adds colour and some rust protection, but it does little about heat.
Which one to choose
If you want colour and corrosion protection, a thin-film coating is a good choice. If you want to keep heat inside the exhaust, protect wiring and lower intake temperatures, choose a thermal-spray ceramic coating. If the budget is tight and the goal is only looks, paint will do.