The concept of heat soaking glass to reduce or eliminate spontaneous breakage due to stone inclusions has been around for decades. Heat soaking involves exposing the tempered glass to elevated temperatures for some period of time.
A typical heat soak process elevates the glass temperature to 550ºF (290ºC) for two hours. Reference BS EN 14179-1 standard. The obvious objective of the heat soak process is to achieve a “break now, not later” result, based on the assumption that any glass panels with inclusions will break during the heat soak process. While there is general agreement on the concept and intent of the heat soaking process, there is not agreement on the outcome. Most agree that heat soaking can eliminate (by destruction) some of the problem panels, but not that heat soaking will guarantee 100% elimination of potential spontaneous breakage due to inclusions.
