The earliest historic mentioning of tempered glass wascalled Prince Rupert's Tears. Molten cup ended up being dripped into ice cool buckets ofwater. That cup hardened immediately, creating teardrop shaped pieces of glass.At the full time, no one understood they certainly were generating what's this time referred to as temperedglass. Ones rips had been exceptionally frustrating bits of glass that could withstand enormousamounts to stress. But they would shatter entering tiny components provided directlystruck using the hammer or perhaps different metal item.