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Glass Enamels
There are two different processes for
making enamels. The first, a traditional method that has been
around for over 2000 years, involves grinding
together small particles of glass
with colorants, fluxes, and other ingredients. This approach
uses a mortar and pestle for small quantities or a machine such as a
ball mill for larger ones.
The second way to make glass enamels is
through a process known as "fritting". This starts with a dry
mixture of minerals and chemicals. The mixture is heated until the particles
melt together, then quenched in water so that it cools rapidly and
breaks into small pieces. These pieces are ground into a fine
powder.
Regardless of the method used, the
resulting particles tend to be around 80 mesh in size,
which is about the same size as commercially available glass powder.
Enamels can be sifted dry, but are most often mixed with a binder
before applying to glass. Application can be by paintbrush, by
airbrush, by screen printing, or by tools such as palette knives or
toothpicks that can be used to transfer the enamel to the glass.
Once transferred to glass, enamels must be fired to maturity.
Different enamels have different firing temperatures, but in general
temperatures for painting or spraying enamels range between
1100F/600C to 1500F/815C. In addition to firing to the
appropriate temperature, care should be taken to use enamels that
approximate the coefficient of expansion (COE) of the glass used.
Major manufacturers of enamels include
Paradise Paints, Thompson Enamel, Ferro, and others. The
characteristics of different enamel brands can vary significantly,
and will be the subject of future tips.
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Copyright 2005 Brad Walker.
All rights reserved.
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