Hard Hat Heat Resistant Aerosol 7715 and 7778 are heat resistant coatings based on a silicone modified alkyd resin. Hard Hat 7715 and 7778 are applied to new, bare steel or blasted steel or properly prepared, coated surfaces such as barbecues, heating tools, hot air guns, exhausts, etc. RUST-OLEUM Hard Hat 7715 and 7778 are intended for minor maintenance work and repairs. RUST-OLEUM Hard Hat 7715 and 7778 provide protection up to a dry heat of 750°C (peak load) when used indoors or in a sheltered outdoor environment.