A Process Of Heat Treatment Which Permits The Rapid Annealing Of Flat Glass

If during the natural cooling of a piece of flat glass and at the moment when its temp is in the neighbourhood of the strain point, intense heating of short duration is applied to the surfaces, their rapid expansion over the semi rigid interior sets up intense compression stresses in the outer layers. By raising the surface temp by less than 100o the stress distribution is such that on cooling to room temperature without any lehr the condition of strain is such as to permit the glass to be cut and bored. The process can be applied in the continuous production of rolled glass.