viscosity of 2 5 u00d7 10 13 poise and has enough internal mobility to relieve itself of strains the strain point temperature is the lower of the two at the strain point temperature the viscosity of glass is higher and the glass will only relieve itself of internal strains after a period of time at the exit end 33 of the lehr 30 the containers are at a predetermined temperature for example for soda lime glass this temperature should be about 950 u00b0 f u00b1 25 u00b0 f the lehr provides a vertical enclosure for the glass containers while being suspended by their necks to travel during the annealing process as seen best in fig6 the heat in the lehr is provided by electric heating element 38 the amount of heat is controlled to reach an equilibrium temperature with the containers the heat mass speed and temperature of the conveyed containers are factors controlling the degree of heating required it will be appreciated that as the containers are conveyed in the lehr the glassware in effect is cooled in a controlled manner by losing heat the desired result as the containers travel through the lehr is that the containers are brought to or below.