A coking process in which tar impregnated refractory products are heated in a muffle within a furnace to a temperature sufficient to cause emission or release of the volatile constituents in the tars and pitches used for impregnation, whether by decomposition or distillation, for a time which is sufficient to remove substantially all of such constituents from the products, characterized by heating the refractory products in a muffle within the furnace while maintaining a positive pressure within the muffle during the emission of the volatile constituents, and thereafter cooling the refractories in a substantially nonoxidizing atmosphere. After the temperature of the refractory products is low enough to avoid any thermal shocking of the brick the brick are removed from the furnace and the muffle.