LOCTITE® SI 5990 is a non-corrosive silicone seal. It hardens by humidity and forms a permanent elastic seal. LOCTITE SI 5990 uses thixotropic behaviour to reduce the migration of the liquid product after it has been applied to the part. It offers excellent temperature resistance. Typical areas of use for this product are applications with an operating temperature range of up to 350°C. Health & occupational safety.