Engraving

The glass plates can be coloured in bulk and made up of one or more layers of colour applied on a sheet of white glass when firing.
Engraving the glass plate using hydrofluoric acid involves either lightening the colours by diluting them or erasing them to show the underlying colour/s.
This process creates a wider variety of tones in the same colour or a multicolour pattern in the same piece of glass by avoiding having to put several pieces together and using lead came.