Heat treating glass is our specialty: We are pioneers and have built our reputation on strength and consistent quality throughout the industry. HGP heat treated glass is available either Tempered or Heat strengthened.

HEAT STRENGTHENED

(Kind HS) is generally twice as strong as annealed glass of the same thickness and configuration. When broken, the fragments are generally somewhat larger than for fully tempered glass, and should be considered for areas where there is concern for glass fall-out as it tends to stay in the opening better than tempered glass. Heat strengthened glass is intended for general glazing where additional strength is desired but not requiring the strength of fully tempered glass. Heat strengthened glass is NOT a safety glazing product.

FULLY TEMPERED

(Kind FT) is over four times as strong as annealed glass of the same thickness and configuration. When broken, it breaks into innumerable small fragments of more or less cubical shape. Intended for general glazing and safety glazing such as sliding doors, storm doors, building entrances, bath and shower enclosures, counter tops, showcases, interior partitions, and other uses where the superior strength characteristics and safety properties of fully tempered glass are required.

PROCESSING

The heat treating process requires that all cutting, drilling and edge grinding fabrication be completed prior to heat treating. Heat treated glass is manufactured by heating annealed glass to a temperature of approximately 1150 degrees F, then rapidly cooling it by blowing air uniformly onto both glass surfaces simultaneously. The color, clarity, chemical composition and light transmission characteristics of the glass remain unchanged during the heat treating process. The physical properties of the glass such as compressive strength, hardness, specific gravity, expansion coefficient, softening point, or its thermal conductivity also remain unchanged. The physical properties affected from heat treating are the significantly higher compressive surface stress and an increased bending strength.

All of our plants heat treat glass - it's our specialty. We use horizontal rollerhearth furnace tempering technology to ensure a high level of quality and performance. HGP heat treated glass is available in 1/8" to 1 " thickness in clear, tinted, reflective or patterned glasses. Not all glasses are available in all thicknesses; thicknesses greater than 1/2" are available in clear only.

THERMAL RESISTANCE

HGP tempered glass withstands approximately 500 degrees F, but is not classified a fire retardant by Underwriters' Laboratories.

LABELING

HGP tempered glass is permanently marked with our logo in a corner of the lite unless otherwise specified.