Painting on Glass

What kind of paint is used? Well there are two types, one is a glass strainers’ colour, and the others are transparent glass colours, or enamels.

Glass strainers’ colour.
Painting on glass is done with vitreous paint, what are vitreous paints I can imagine you saying.
Well they are a mix of ground glass and a metal pigment oxide.
Metals like iron, is where we acquire black and brown colours.
Cobalt, for blue.
Manganese, for purple and others are used to make a fine powder.
The power is than mixed with a binding agent like gum Arabic, turpentine or Guinness which works quite well.

Enamels are similar to glass strainers' colour, but fired at different temperatures.

They are then applied to the glass and most importantly fired in a kiln at high temperature for permanent adhesion to the glass. These paints have a limited range of black, brown, red and grey-green. If you study a painted window, in particular the folds of a dress, you will see the artist uses the paint mix, lightly in places and very heavily in others area’s.
What the artist is doing is controlling the light coming through the glass to give an impression of a fold. Or you might say the artist was painting with light.