Keeping Copper Inclusions Bright
This is part of an
ongoing series about inclusions. For basic information about
inclusions, click here.
Copper is commonly used as an inclusion between two layers of
glass. A typical firing schedule involves sandwiching a thin
piece of copper (often cut or punched into a desirable shape)
between the layers, then firing to a full fuse. In most cases
the copper will turn a purplish color, with the darkness of the
purple varying depending on the type of copper used, the length of
the firing, and the firing temperature.
Often, it's desirable to avoid the purplish color change and
maintain the bright copper color after firing. This can be
done by coating the copper prior to firing. Although some
people report success with borax solutions, Klyr-fire, or related
products, the most dependable technique is to coat the copper with a
clear glass paint.
One brand of paint that works well is Unique Glass Color's
clear (GC950T). This can be applied to copper with a brush,
but for best results an airbrush should be used. It's also
helpful to scrub the copper slightly prior to applying to give the
metal some "tooth" and help the paint stick better. (A
Scotchbrite brand scouring pad or a Kemper greenware file will
work.) After the paint dries, sandwich the copper between two layers
of glass and fire as normal. As with any inclusion, small
trapped air bubbles are possible, so a good bubble soak is a
Copyright 2006 Brad Walker.
All rights reserved.
Thanks to Tom White for
suggestions incorporated in this tip.