The present invention relates to a molten, fluid refractory product comprising, in weight percentages on the basis of the oxides and for a total of 100% of the oxides:ZrO2+Hf2O: remainder to 100%4. The present invention also relates to kits to perform such methods. R1-R13, m, n, o, and p are disclosed herein. Each of the filled molds are pressed in a press at a predetermined temperature at a predetermined pressure for a predetermined period of time sufficient to harden the mixture into a hardened slab.