FastFire Liquid, 1 Liter, 38161About this product 15 minute benchset 27 100 mixing ratio Working time of 7 9 minutes Setting expansion & thermal expansion: 1. 0% 500 psi FastFire 15 is a fine grain phosphate investment which requires only a 15 minute benchset before placing molds into a hot oven for rapid burnout. It produces accurate, smooth castings using either the ringless or metal ring technique. Optimum fit is achieved for all crown and bridge alloys through dilution of the