Painting on Glass
These "paints," which like traditional stained glass paints are actually
finely ground glass particles with a relatively low melting point, are available
in both transparent and opaque colors. They are applied, and then fired onto the
glass using a kiln.
Because glass enamels are made of tiny glass particles, care must be taken to
ensure that they are compatible with the base glass being painted on. As with
any other glass, using incompatible enamel will result in cracking or poor
adhesion.
Care must also be taken when using glass enamels that the fine particles are
not inhaled. A respirator or mask is recommended to prevent this, as inhaling
fine glass particles can cause silicosis, a serious and potentially fatal lung
condition.
There are a number of ways in which glass enamels may be applied, but in most
cases the enamels are applied and fired in several layers. This maintains the
integrity of the colors and also helps to achieve effects that would not be
possible in a single firing. It is not uncommon for enamels to require four or
five or more firings before the work is complete.
The most common ways to apply glass enamels are by brush, by dry sifting the
enamels onto the glass, and by screen-printing.
** Brush application
To apply enamels with a brush, you must first mix the glass particles with a
liquid (called a "medium") to obtain a paint-like consistency. Mediums may be
oil or water-based, but water-based mediums have the advantage of generally
being safer and easier to clean up. The key criterion is that the medium fires
clear without leaving a residue.
The proper consistency for painting is approximately one part enamel to two
parts medium, but this can vary depending on the particular enamels used. It is
a good idea to mix the paints on a smooth surface (a sheet of window glass is
ideal), adding the water drop by drop until the desired consistency is reached.
Sometimes the paint will dry out a bit during painting and you will need to add
a few extra drops of water.
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