What is tempered glass? Tempered glass is float glass that has been heated and then cooled rapidly to increase its force or pressure on its surface, its physically strength is times of normal float glass. What is heat strengthened glass? Heat strengthened glass is a kind of glass between float glass and tempered glass, it has part advantages of tempered glass, such as high strength, meanwhile it avoids the weakness of tempered glass, such as flatness problem, spontaneous breakage and completely damage when broken. Why heat soak test is needed for tempered glass? Temperd glass is used in building industry as safety glass, but the weakness of spontaneous breakage affects its use. Heat soak test is a treantment to nickel-sulphide inclusions, which is the main cause of spontaneous breakage. Wooden crate Thickness: 5mm-25mm Min size: 300*300mm Max size: 3300*9500mm/2440*12000mm.