WRAP Report Addresses Glass Recycling

A report recently published by theWaste & Resources Action Programme aims to help the glass industry to absorb more green glass in its current production.

The two-year Colourite project, carried out for WRAP by Glass Technology Services Ltd. in close co-operation with container glass manufacturers, explored the technical and aesthetic barriers to increasing the amount of recovered glass cullet from mixed color collections that can be used in the production of new clear glass containers.

The project objective was not to counteract the growing level of mixed color collected glass, but to highlight the affects that higher levels of mixed color collection will have on clear glass color quality in the future.

"In simple terms, the UK container industry has a large unsatisfied demand for clear cullet but an oversupply of green cullet. This imbalance is being exacerbated by the growing trend towards mixed color collections, which results in higher levels of color contamination and the additional loss of clear cullet during the sorting process," said WRAP’s Glass Technology Manager, Andy Dawe.

"In commissioning this project, we took a pragmatic view that these issues are here to stay and the aim of the project was to find ways to maximize the amount of cullet that container manufacturers can use in their furnaces from these sources. We approached the problem from both ends of the quality spectrum; how good a glass can be made and how good does the glass have to be to satisfy brand owners, packaging designers and the consumer."

The first phase of the project focused on technical solutions to allow clear glass furnaces to produce an acceptable product using color-contaminated cullet. Culminating in full scale manufacturing trials, this work has established that an acceptable quality can be achieved cost effectively by adding commercially available decolorisers to the furnace.

Another important result of the work has been the development of a specification for color contamination of processed glass which makes use of the new sampling method and has been agreed by both the glass processors and the container manufacturers.

Tackling the issues from the end customer perspective, the second phase of the project explored the impact that using various shades of glass (clear versus shades of green) for food and drink containers has on consumer perception and attitudes.

Conducted by the Psychology of Design group at the University of Leeds, the research has shown that, in many cases, the color and clarity criteria adopted by glass manufacturers, brand owners, and marketeers are much more stringent than those required by the consumer.

The full report is available in PDF format on the WRAP website at www.wrap.org.uk.