Method of thermal tempering transparent glass bodies

Claim 1

rotating the tubular body of glass while concurrently exposing same to a source of energy consisting essentially of infrared radiation having wavelengths in the wavelength range of 0.7 microns to 3.0 microns and thereby transmit at least 90 percent, but not all, of the infrared radiations in the wavelengths of 0.7 microns to 3.0 microns through the body of the glass, and the remaining portion of infrared radiations within said wavelength range being absorbed throughout the entire body of glass subjected to said radiation to thereby substantially uniformly heat all portions of the body of glass subjected to said radiations above the strain point temperature of said glass, but below the deformation point temperature thereof, whereby all portions of the glass body subjected to said radiations reach a temperature above the strain point of the glass at the same time;