Acid Etching

 

Copyright © 1996-2017  Geoffrey Wallace Stained Glass

 

Aciding is a technique which allows more than one colour to appear in a single piece of glass.  It is the process of removing a layer of colour from a base of a different colour on what is called flashed glass.  Flashed glass is also a mouth blown glass but at the time of manufacture the glass blower first gathers one gob of molten glass on the end of the blow pipe and then immerses this gob in a different colour of molten glass thus coating the original gather with a different colour.  The glass is then blown into a cylinder as with pot colour glass and the resulting sheet has a thin layer of different colour on one surface.


In the example below, the base glass is clear with a flash layer of ruby.  To remove the flash, the glass is first coated in a resist that is then cut away to expose those areas that are to be etched.  The glass is then immersed in hydrofluoric acid which will eat away at the exposed surface until the base colour appears.

Raw flashed glass cut to size.

Flashed glass after aciding.

Trace lines painted and fired.

First matte.

Second matte.

Silver stain.

After painting and staining, the resultant pieces of glass now actually contain 3 colours, white, red and yellow, dramatically increasing the colour palette of the glass artist.  The glass can also be carefully wiped with hydrofluoric acid to achieve graduated exposure of the base colour as in the wings of the angel on the right.