Abstract: A mixture including glass fragments is located in a containment vessel and is processed in a kiln to form a commercially useful building product. The mixture is initially heated over a first time period to a first temperature intermediate the glass transition point temperature and about 950° C. or 1,100° C. (Section A). At the first temperature the glass fragments slump and bond to each other and the mixture is soaked at this temperature for a second time period (Section B). After reducing the temperature (Section C), the mixture is annealed for another time period (Section D). Finally, the kiln is cooled to allow the mixture to be removed (Section E).