We recently started making our own furnace cement. It has been interesting learning to mix a highly viscous material (almost 500,000 centipoise; water is 1 cps) and then fill caulking tubes, but Yankee Ingenuity has prevailed. Our unique ingredients are soapstone powder, and very small strands of chopped fiberglass.
Our cement has terrific adhesion to cast iron, steel, soapstone, and gasket, can be applied in very thin beads, as well as thick strands, won’t slump or run, and is a great performer at high temperatures!
Below, engineer Ken Blum inspects a batch of cement as it turns in our new old mixer!