A new material, which has the potential to replace zircon sand for secondary prime dips, and possibly the first prime for some casters, has been developed. REMASIL® 60 RG100, based on a 60% alumina, alumino-silicate material, is a high mullite product which has been fired to a high temperature. It is then sized to provide the optimum match to zircon sand (the distribution is slightly coarser than zircon.) Laboratory testing (MOR, permeability and thermal expansion) was performed to determine how closely the RG100 sand performed versus zircon. The test results revealed some small differences between the two sands. The method of application (fluid bed or rainfall sander) resulted in only minor differences in the permeability or MOR results.