There is also an article in the June 2007 Lapidary Journal. They
recommend using turpentine in between the coloring layers.
I just finished teaching a class on this for our metals group. This
is what we did:
Patina the copper (I used horse-urine soaked sawdust).
Clean the metal up with soap and water and let it dry thoroughly.
Apply the colored pencil using the well-patinated areas of the
Using a cotton ball, dab turpentine onto the colored area. Let dry
Continue coloring./turps until you are "happy" with the result.
Spray with a matte sealer (we used Krylon) and set.
We did NOT get the kind of color density that you see in the Deb
Karash material but we did OK. Drawing and blending colors (and
shading) worked well. I made a piece copying some prehistoric cave
art and it came out well with the details noticeable.