| What temperatures will the impregnant withstand?
For resins, 350°F is the highest temperature generally recommended for continuous usage, but resin will withstand 450°F temperatures for short intermittent periods. Where parts are water-jacketed or forced air-cooled, such as in automotive cylinder heads and blocks, much higher surface temperatures, up to 1400°F, can be withstood without resin failure since resin remains strong and solid in the porous areas of the cool side and though it may char next to the hot side, it never melts and is protected by the thermal conductivity of the metal. For continuous operating temperatures greater than 450°F without water or air cooling, special resins or epoxies containing silicons can be used. Another technique is multiple sodium silicate impregnations. With special baking and curing they can then withstand temperatures in excess of 1000°F.
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