it also says this, my glass bowl has white bits in it.
Copier also pioneered the use of Graniver, a brightly coloured semi-porous type of glass with sand added to the batch which was mainly used for making cactus and flower pots. He also made extensive use of Tin crackle, a process in which tin chloride was fused onto the hot glass before blowing it out further. The result is a decorative matt white cracked surface.