Once the piece has cooled, why do the beautiful colors
disappear when I touch them? It seems if I run my finger over
them, they vanish like magic.
Basically the reason you have the colors is a thin film which alters
how the light reflecting to you is filtered. The thickness of the
film changes which colors are removed, and which left. Because it is
a thin film the moment to touch it or put oil or a sealer on it the
lighting conditions change and usually the surface is damaged.
Nicholas Lacquer and Incralac are both supposed to let you keep the
colors while still protecting them. best Charles
Interference colors are explained here:
Here is a similar coloring method.
and from: Cupric Nitrate Patination of Metals - Ganoksin Jewelry Making Community
The finished product may also have some form of protective coating,
although this patina is tough and not liable to damage if applied
Traditionally these would include waxes, vaseline and oils. Also
available are the spray sealers and lubricants mentioned above. These
work as water does in intensifying perceived color on the patina
surface. The exact effect will depend upon the refractive index of
the coating involved, its evaporation rate, viscosity, etc. One
should make samples with various colors and different coatings for
reference. Oils and waxes tend to darken the color. The spray
acrylics tend to make the patina resemble green paint and I usually
use them sprayed from a distance for a thinner more subtle effect. In
general the use of such coatings is for aesthetic reasons rather than
My favorite is clear auto enamel: intended for outdoors, intended
for different temperature ranges, intended for metal. Nicholson
Lacquer (used on High School marching Band instruments) is very good.
Charles Lewton-Brain/Brain Press
President, Canadian Crafts Federation
Box 1624, Ste M, Calgary, Alberta, T2P 2L7, Canada
Tel: 403-263-3955 Fax: 403-283-9053