PURPOSE: To evaluate a refractory material easily and speedily by measuring the extent of the spreading of molten burnt ash on the surface of the refractory material.

CONSTITUTION: A small constant amount of burnt ash or clinker 2 is placed on the refractory material or a ceramic plate 1 whose surface is smooth and heated to constant temperature in an electric furnace. The ash 3 melted by the heating flows on the surface of the refractory material and spreads and tends to spread larger and larger as the sticking property to the ash is smaller and smaller. For the purpose, the diameter (d), area (S), etc., of the spread ash are measured to compare and evaluate the sticking property.