This section is divided into the following
categories.
Chemistry of Colours.
Glass production methods.
History of Stained Glass.
Styles.
Window Gallery
CHEMISTRY OF EARLY COLOURED GLASS
Apart from the three basic ingredients of sand ,soda and lime the following
were
added.
MANGANESE
Even when using the best quality ingredients available the "natural" colour of
glass was pale green (aqua) this was due to impurities in the ingredients; mainly the iron
oxide in sand . So manganese was added to produce clear glass.
Later this
was replaced by selenium possibly because when glass made with manganese is exposed to
strong sunlight for any length of time it turns amethyst the depth of colour depends on
the amount of manganese in the glass and varies from a pale tint to a deep solid colour.
The effect can be best seen when individual pieces are removed from a window and the edges
which have been protected by the lead came and putty can be seen.
SEE PICS
COBALT
When added to the melt this produced a deep rich blue