Amber colours with iron and manganese

This work deals with pot melted amber glasses using iron and manganese as the principal colourants. It is based on theoretical colour predictions using the extinction coefficients published in the book by Bamford. The initial work looks at a pair of glasses for which no colour measurements were available while the second considers the influence of iron and manganese on the colour. Finally, colour measurements were carried out on a small number of glasses with known chemical compositions. In order to create a reasonable fit between prediction and measurement it was necessary to assume a very small concentration of the iron/sulphur chromophore present in reduced amber container glasses. Accordingly, transmission data was taken from a typical soda-lime-silica container glass amber. To convert these values to linear absorption coefficients it was necessary to know the concentration of the amber chromophore present in a typical iron/sulphur amber glass. Estimates for this were taken from a paper by Harding. The fourth glass in the group contained a significant amount of selenium and so it was necessary to include an iron selenium chromophore using the extinction coefficients from Banford also given in his book.