Molten glass is spooled at one end of a blowpipe, removed from the crucible, blown into to adjust its shape, then placed in a mold to work it into the desired form. After cooling, the top of the glass is finished by removing any unwanted parts. A blade is used to make a scratch around the glass at the point it is to be cut, and the glass is readily divided by torching the scratch. The freshly cut edge is polished, then heated by flame and slightly melted to create a smooth rim. This must be done carefully because thin glass loses strength if the flame is too strong, but the rim is less smooth if the flame is weak. Finding that balance is crucial because it can drastically change the feel on the lips.
Thanks to this process, handmade glasses have a thin, delicate rim, where that of machine-made glasses is thick and round. Human lips can feel that subtle difference, and it can even alter the taste of the drink. The difference between machine-made and handmade glasses is obvious to the lips.
