The multifunctional role of cullet as an endless cradle-to-cradle sustainable material has resulted in its increased use within the glass industry. This is even more pronounced in light of recent spiralling energy prices. However, availability of high quality post consumer cullet is a challenge due to contamination during the recycling process. To-date, to the author's knowledge, there are no systematic methods to determine the type of contamination and also to express the severity of said contamination in a truck load or a pile of cullet. This work establishes a practical quality index to specify cullet quality by type and severity of contaminants. This coding method can be used by all parties involved in the life cycle of cullet (i.e. cullet suppliers as well as glass manufacturers).
