Tempered glass granularity standards in GB15763.2 "Tempered Glass" has detailed provisions. For the 50mm x 50mm box, the granularity requirements are as follows: for 3mm and below, at least 30 grains are required; in the range of 4-12mm, 40 grains are required; and for particles above 15mm, the minimum standard is 30 grains. It's worth noting that if a pellet is completely within the frame, each grain counts; however, if the pellet is pressed by the frame line, it only counts as half a grain.
While tempered glass has the advantage of high strength, it also has its limitations. First, tempered glass cannot be cut or further processed once it is finished, so the shape must be predetermined at the time of processing. Second, despite the increased strength, tempered glass carries the risk of self-blowing, a characteristic not found in ordinary glass. In addition, the toughening process can result in wind spots, or unevenness, on the surface, due to the rapid cooling of the glass after heat treatment, which reduces the internal crystal gaps and increases the pressure, resulting in some thinning of the glass after toughening.