Benjamin Moore Industrial Maintenance Coatings, M64 Silicone Akyd High Heat Coating. It is an aluminium paste based alkyd which is formulated for kilns, incinerators etc. for heat resistance up to 800 degrees. M64-80 is the product code for black. Use it as a primer and finish coat and apply two or three thin coats instead of one or two heavy and follow recoat time carefully. Can be ordered from any BM retailer. Get a copy of the TDS and read carefully before application.
Good Luck,
Vandi.