Heat Strengthened & Tempered Glass

Solar Seal has been heat treating glass for many years and we have seen a lot of changes in that time. It used to be that glass was tempered vertically and held in place by tongs. This method was replaced by horizontal roller hearth ovens which produced better quality tempered and heat strengthened glass. The newest design in glass processing furnaces is the convection oven and Solar Seal is proud to say that we are operating one of the best in the industry. The convection process allows us to heat treat glass faster and with better quality than ever before.

Solar Seal offers both heat strengthened and fully tempered glass. Our heat treated glass meets or exceeds the US Federal Standards CPSC 16 CFR 1201 catagories I and II and complies with ANSI Z97.1 as well as ASTM C-1036 and ASTM-C1048. Heat strengthened glass has approximately twice the mechanical and thermal strength of annealed glass of equal thickness. Fully tempered glass has approximately four times the mechanical and thermal strength of annealed glass of equal thickness. Fully tempered glass as compared to annealed glass has improved resistance to rapid temperature changes and impacts, improved strength, and if broken crumbles into relatively harmless fragments as opposed to large shards with sharp edges and corners. All of Solar Seal's heat treated products are stamped with a ceramic logo (unless otherwise requested) indicating the process it has undergone. Solar Seal offers fully tempered glass in thicknesses from 1/8" to 3/4".

Once the glass has been heat treated, it can not be cut or drilled. Post heat treated field alterations such as edge grinding, drilling, or acid etching can cause failure. Tempered glass is also more prone to spontaneous breakage than annealed glass. This can result from impact, weld splatter, wind borne debris or internal inclusions in the glass like nickel sulfide. Heat strengthened and tempered glass may contain surface waves caused by contact with the ceramic rollers inside the furnace. This distortion is most visible when viewing reflected images from a distance. Roller distortion is inherent in the heat treating process and is not considered a defect. Another common characteristic of heat treated glass is strain pattern or iridescence. This strain pattern is most visible under certain lighting conditions and when viewed at an acute angle. Strain pattern is inherent in the heat treating process and is not considered a defect.

For more information on heat treated products please contact your sales person, customer service representative, or view ASTM C-1036 and ASTM C-1048.