Heat-resistant varnishes

When you have to paint parts whose surface is likely to rise in temperature, you must use specific protective varnishes and in particular high-temperature varnishes, capable of withstanding up to 700° Celsius. What is a high temperature varnish ? It is a varnish capable of withstanding a higher level of temperature, for a certain number of times. For example, the temperature resistance can be 300°C for 30 min, or 400°C for 2 minutes.

What happens when a varnish is heated and brought to high temperature ? The dried film may begin to yellow, or blacken, crack, bubble, crack and then burn, emitting smoke or even flames. The composition: in general, a very good resistance to heat implies that the varnish is single-component. As for classic bodywork varnishes, they withstand honorable levels of 200 to 250°C without flinching.

Uses for high temperature varnishes

We talk about significant heat levels to classify these products. The classification of these transparent finishes begins at 300°C. Varnishes capable of withstanding levels of 600 or 700°C are sometimes found. In general, the indications on the data sheets do not give many details on the times and durations of exposure to heat noted during tests and laboratory tests.

Often, moreover, we do not know precisely, or not at all, the surface temperature of the object on which the high temperature varnish is intended to be applied ! What are the uses of high temperature varnishes ? They are very often requested to be used as protective finishes on heaters, stoves, brake calipers, engine blocks, exhaust pipes.

Can we apply a classic varnish as a replacement ?

Often, we confuse the temperature of the core and the surface of an object. For example, the surface of an engine block rarely rises above 150°C.
There are a variety of very good polyurethane acrylic varnishes which have the resistance properties necessary to withstand these relatively low temperatures without problems. High temperature varnishes are, it should be known, quite rare and it is difficult to obtain them.

About high temperature paints

Paints consist of a binder added to pigments. Once the correct binder has been chosen, paint manufacturers need to be sure of the type of pigments to be used ! Indeed, many pigments are damaged, discolored or darkened when exposed to high temperatures. The most resistant colors and the easiest to find, especially for very high heat levels, are aluminum and black, very logically ! Yes, there is a series of colored pigments of the yellow and red type that can withstand 300°C.

Anti-UV varnish
Ceramic varnish