UK glass manufacturers prize clear glass – or flint – most highly because and while most glass made in the UK is clear, by far the largest proportion of the glass waste stream is green. For this reason green is prized the least. Completely mixed glass cannot directly be used in the container re-melt industry, where colour purity is vital, and must instead go to alternative uses such as aggregates or for sorting into separate colours.

A number of UK glass recycling companies have invested in new glass sorting technology in recent years, which has enabled them to sort and separate quality mixed glass to a high standard, making colour-contamination less of a problem.

Despite increasing competition from alternative glass markets such as aggregates, energy costs and limits on carbon emissions mean that container manufacturers are keen to use more recycled cullet.

But although many glassmakers would argue container manufacture is the best use of cullet, as glass can be re-melted countless times, alternative uses such as grit blasting, use in road surfaces and water filtration are also of note.

Prices shown are for container glass in £ per tonne ex works collected by a contractor/glass recycling plant.