Kiln-formed Glass
Kiln-formed glass is an ancient technique that dates back to Egyptian times and which today creates the sophisticated, original designs for which Fizgig Glass is known.
The process involves heating two or more pieces of glass together, causing them to melt into one unit.
The decorative designs are created by fusing coloured glass granules between the layers of glass. When air becomes trapped between the layers, it creates the characteristic elements and textures found in kiln-formed glass.
Further decorative detail can be added to the design by using metals and metal oxides to introduce unusual colouring and vitality to the pieces, or by painting and firing metallic lustres onto the surface so that the glass exudes a delicate brilliance.
To make a three dimensional piece the glass must be fired twice, firstly to fuse the decorative elements and glass together and then again into a ceramic or steel mould to create the desired form. Controlling the firing temperature is a crucial part of the process and is learnt by trial and error with happy – and not so happy – accidents along the way.
A number of techniques may be used together and in combination with material experimentation the most exciting discoveries can be made. The manipulation of glass using this ancient technique offers endless possibilities for the curious contemporary designer.
Glass with its peculiar and often unpredictable behaviour is as challenging now to the craft practitioner as it was in ancient times.
Dichroic Glass
Dichroic glass is the stunning, eye-catching form of glass used in Fizgig’s jewellery.
The word “dichroic” is derived from the Greek, “dichroos”, meaning two coloured and referring to the optical effect observed in certain crystalline materials in which different colours are seen when the crystals are viewed from different angles. The glass appears to have one colour when viewed in transmitted light and another in reflection, and a third colour when viewed at a 45˚ angle.
It is the same effect seen in the iridescence of humming bird feathers, the shimmer of fish scales and the spark of fire opals – even the glisten of an oil slick on water.
This vibrant visual effect is achieved from extremely thin coatings of metal oxides on the glass transmitting and reflecting light as the glass is rotated. The resulting colours are pure, saturated, single wavelengths of light that appear to originate from within the dichroic piece.
The technique was developed in Germany by Dr Arthur Pfeiffer over a century ago and dichroic glass was probably first made in the late 1880s in Germany. But it was not until the 1960s, when NASA developed the modern process for making it – known as “thin film physics” – that its application in such areas as medicine, solar energy, armaments, photography, and particularly American aerospace programs began to inspire artists and sculptors.
Today, glass artists use glass which has been treated with metal oxides such as titanium, magnesium, zirconium, beryllium, chromium, selenium, yttrium and tin. The oxides are vapourised in a vacuum with an electron beam gun. The vapour then floats up to become attached to the surface of the glass in the form of a crystal structure. Although there may be as many as 30 layers of these materials, the total thickness is only 3 to 5 millionths of an inch, creating the brilliance that allows glass artists to create such complex work.
