A conventional way of colouring glass is to introduce transition metals. These polyvalent ions colour the glass while the redox level controls the oxidation state of the metal ions and thus the colour. The refining agents used for crystal/handmade glass are also polyvalent ions and will have a large influence on the redox equilibrium in the melt. This paper looks at the influence of different metal ions on copper. Antimony, arsenic and cerium are of interest as refining agents. The reducing order for copper is investigated and an extended correlation between the refining agent and the colouring agent was made. The study involves the refining agents arsenic, antimony and cerium combined with the colouring agents copper, manganese, chromium and iron.
