fibers by ramming the plastics into molds with an air hammer in the first trial one block each of kaolith 85pb and kaolith 85pb refractory with polypropylene fiber was placed in position as a furnace door the furnace was heated at a rate of 1000 u00b0 f per hour to 2500 u00b0 f at 2500 u00b0 f the furnace temperature was held for 4 hours and then coled at a rate of 300 u00b0 f per hour in the second trial one block each of kaolith 80as and kaolith 80as refractory with polypropylene fiber was placed in the furnace door the furnace was fired at a rate of 1500 u00b0 f per hour to 2500 u00b0 f at 2500 u00b0 f the furnace temperature was held for 4 hours and then cooled at a rate of 300 u00b0 f per hour in a third trial all four types of bricks were inserted into a furnace held at a temperature of 2500 u00b0 f the bricks remained in the furnace for one hour and were then removed in both types of tests the kaolith 85pb refractory specimens experienced extensive blistering a result common to plastic refractories with the surface being easily fractured kaolith 85pb refractory specimens containing polypropylene fiber experienced blistering to a lesser degree the kaolith 80as refractory specimens experienced extensive cracking while the kaolith 80as refractory specimens containing polypropylene fiber experienced less cracking two trials were conducted in an alloy foundry to determine the applicability of this rapid fire technology to induction furnace linings the trials were conducted in 700 pound.