Mouth-blown glass
Mouth-blown glass is glass shaped by a glassblower using a blowpipe, as opposed to being drawn, rolled or floated by a machine. In stained glass, it means sheet glass made by blowing a cylinder, which is opened and flattened, or by blowing and spinning a disc, as in crown glass.
The process leaves the glass with small variations in thickness, a faint surface texture and sometimes bubbles, called seeds. These flaws refract light and give the glass life, and they are why mouth-blown glass is the preferred choice for restoration and for high-quality new windows.
It is also called antique glass or, if made by the cylinder method, muff glass.