Mark,
The horn was first dyed with aquafortis in three applications. With each application, I spread a thin even coat over the horn, then heated with my hot air gun, producing a nice light yellow color. After setting and securing the butt, I heated the horn again and applied dark walnut oil based stain, selectively wiping it and also sprinkling black tempura paint on the stain. This is basically following the method Scott Sibley (bigbat) has in his book. I'm still experimenting with the antiqueing, seeing what works for me...
Scott M.