The glass pens made by artisan Takeda Mio (竹田海緒) are made of borosilicate glass, which has more thermal shock resistance than other hard glasses. Unlike soda glass which has a relatively low melting point, borosilicate glass melts at 820°C. The glass is not melted in a kiln, but processed individually above an oxygen torch and then shaped while it is malleable, much like the process of candy making. Borosilicate glass is light and durable, making it ideal for glass pens.
Takeda Mio graduated from the Glass Program from Tama Art University's Department of Crafts. She is a glass artist from Kikai Island in Kagoshima Prefecture, Japan.