Glass Specifications

Industry specifications

There are two main types of contamination in glass: material contamination and colour.

Contamination

Three levels of contaminants are stated as below:

  1. Unacceptable contaminants Any medical or chemical refuse, needles and syringes; bottles and jars containing any liquid or solid hazardous or toxic material, coal or coal dust.
  2. Critical contaminants Ceramics such as crockery or earthenware, Pyrex cookware, Visionware glass saucepans, inorganic materials such as bricks, concrete, gravel, stones etc and non-container glass such as flat glass, laboratory ware, light bulbs and tubes.
  3. Hazards All non-magnetic metals, particularly aluminium and lead. Wire, strapping, wood, plastics, textiles and materials.

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Colour

There are three main colours of glass: clear, also known as white or flint; green; and, brown, also known as amber. Different glass collectors specify different degrees of colour separation in container glass.

In recent years some companies have developed high-tech colour sorting equipment in order to combat contamination by other colours. Some collectors will also take mixed glass as well as colour-separated.

Cullet

In 2006, the Waste & Resources Action Programme published a standard, known as PAS 101, which gives a specification for recovered glass and outlines grades that can be applied to tipped loads.

PAS 101 seeks to harmonise various independent specifications to provide a comprehensive specification for all raw container glass collected in the UK for recycling. It introduces a four tier grading system for raw cullet quality – grades A to D – according to the degree of colour separation, contamination and particle size.

Grade A

Cullet type

White flint (clear) Amber (brown) Green
Permitted contaminant Other colours 4% Other colours 5% Other colours 5%
Contamination: No more than 0.5% organic, 0.1% ferrous and 0.2% non-ferrous.
Grade B

Cullet type

White flint (clear) Amber (brown) Green
Permitted contaminant Amber (brown) 6% Other colours 15% Other colours 30%
Contamination: No more than 0.5% organic, 0.1% ferrous and 0.2% non-ferrous.
Grade C

Cullet type

White flint (clear) Amber (brown) Green
Permitted contaminant Amber (brown) >6% Other colours >15% Other colours >30%
Contamination: Up to 1.0% organic, 0.2% ferrous and 0.4% non-ferrous.
Grade D

Cullet type

White flint (clear) Amber (brown) Green
Permitted contaminant Amber (brown) >6% Other colours >15% Other colours >30%
Contamination: Up to 3% organic, inorganic, ferrous and non-ferrous.

One independent company’s specifications are set out below:

Berryman’s specifications

Cullet should consist of container glass only. Glass should not be deliberately crushed and bottles should be kept as whole as possible. If a load has contamination levels greater than in the guidelines below, it may be reclassified as mixed for use in alternative markets.

Maximum degree of cross-colour contamination permissible in colour separated glass
Cullet type White flint (clear) Amber (brown) Green
Permitted contaminant Amber (brown) 2%, green 2% Other colours 20% Other colours 20% (exc blue)

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Quality Protocol for Flat Glass

WRAP published a Quality Protocol for flat glass in January 2009. The Quality Protocol sets out criteria for when the material is no longer classed as waste and is intended to increase customer confidence in the material.

letsrecycle.com price specifications

Prices shown are for tonnages of container glass (essentially bottles and jars) delivered to a cullet collector who will clean and sort the glass ready for use, or for further checking, by a glassmaker.

The price paid for recycled glass tends to be relatively stable, meaning that long-term contracts come with a good degree of security. This is because the glass industry is not dependent on the export market and there is also a strong domestic market for glass.

The guide price for mixed glass typically reflects the sum that may be paid at the weighbridge by the aggregates sector and some glass industry recyclers for the mixed material.

A variety of contractual arrangements exist with local authorities who are the main provider of glass for recycling. Traditionally the main route of collection has been via bottle banks which are usually owned by the local authority or leased from a glass collector or waste management company, however increasingly the material is being collected at the kerbside.

Councils may face a charge per tonne for material collected via bring-banks. The value for the glass is then deducted from the charge resulting in a reduced overall charge/profit to the council following the deduction.

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