Glass that has been collected for recycling is called cullet. Glass container manufacturers recycle cullet, combined with soda ash, limestone and sand, to create "new" glass. In 2003, glass made up 5.3% of the municipal solid waste stream by weight, and of that, about 22% of glass containers were recycled.
Using recycled glass to make new glass packaging reduces consumption of raw materials, extends the life of plant equipment and saves energy.
The best glass recycling practice is to sort glass by color (clear, green, and amber), as mixed glass has little or no value to container manufacturers. Materials to keep out of the glass recycling mix includes ceramic cups and plates, clay pots, drinking glasses, light bulbs, and mirror and window glass. These items are not recyclable and will contaminate a batch of cullet.