In recent years there has been a strongly growing awareness that Heat-Strengthened (HS) glass provides many advantages compared to Fully Tempered glass when used in window and curtainwall applications where impact-safety is not a requirement. The absence of risk from spontaneous breakage, the better retention in the glazing system ( if broken) and the improved surface quality are giving strong recognition to HS glass worldwide as a “first product of choice “ for façade glazing.

“Arc-HS” glass is a “semi-tempered” glass in which the hot glass is cooled similarly to FT glass, but for a longer period which results in much lower compressive stresses in the ‘external envelope” of the glass and a much thinner, weaker tensile zone. As a result, Arc-HS glass does not have the impact resistance of FT glass and is therefore not a true safety glass. Fragmentation of HS glass is typically into large pieces which,
however, tend to remain “in situ” especially when used in Insulated Glass Units where the perimeter silicone sealant holds the fragments in place.