cullet

Broken glass pieces.

Cullet can be melted in a glass blower’s furnace (with or without the addition of glass batch) and can be used for casting in a kiln.

Cullet is used to describe both “new” glass produced in the cullet format as well as broken “used” glass being reclaimed in a recycling process.

The word cullet is a variant of the 19th century collet – glass left at the end of a blow pipe or punty.