V.H.T. is an extremely fine-grained phosphate investment for direct-firing ceramics with an ample working time of 4-5 minutes. This outstanding refractory material can withstand repeated firings at furnace temperatures of up to 1,200 degrees C (2,200 degrees F). Compatible with high-expanding porcelains, V.H.T. is the pioneer high temperature refractory material that has proved itself in many thousands of restorations since its introduction in 1984.