What does cullet mean?
Cullet is broken or waste glass, particularly scrap that has been collected for recycling and returned to a furnace to be melted and formed into new glass products. The word belongs mainly to the vocabulary of the glassmaking and recycling industries, where it functions as a mass noun — one speaks of buying, sorting, or crushing cullet rather than counting individual pieces. Its importance is practical as well as environmental: adding cullet to the raw batch lowers the melting temperature, reducing the energy required and cutting the consumption of virgin materials such as sand and soda ash. Glass recyclers typically sort cullet by colour, since clear, green, and amber glass must generally be kept separate to produce acceptable new containers. Though unfamiliar to many outside these trades, cullet is a useful term precisely because it names a material central to one of the most successfully circular forms of recycling.
nounBroken or waste glass, especially scrap glass that is collected and remelted to make new glass products.
- Scrap or broken glass, especially collected for recycling and remelting in glassmaking.
"The glassworks buys crushed cullet by the tonne and melts it down alongside fresh raw materials."
"The factory mixes about thirty percent cullet into its furnace batch to lower energy costs."
"Workers sorted the cullet by colour before sending it off for recycling."
Cullet is normally treated as a mass noun; a plural form is rarely needed and seldom seen.
"Several truckloads of cullet arrived at the plant before dawn."
Every tonne of cullet melted into new glass saves roughly the raw materials it replaces — which is why your empty bottle may literally become its own next life.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cullet
The origin of cullet is somewhat obscure, though it has been in use since at least the seventeenth century in English accounts of glassmaking. It is often thought to derive from, or be related to, the French word collet, meaning a collar or neck, possibly through a sense connected to the neck of a glass vessel or to small cut-off fragments. Whatever its exact source, the word established itself early as the standard trade name for waste glass destined for remelting.
How cullet is actually used
Cullet is almost always treated as an uncountable mass noun, so phrases like "a lot of cullet" are standard while "cullets" is rare. It is chiefly a technical term used in glass manufacturing, recycling, and waste-management industries rather than in everyday conversation.
Easily confused with cullet
A cutlet is a thin slice of meat or a breaded patty of food, while cullet is scrap glass used in recycling.
A collet is a metal sleeve or collar used to clamp a tool or workpiece in machining, whereas cullet is recycled broken glass.