I experimented with two types of dyes: J.E. Moser's Aniline and Stewmac's ColorTone. The J.E. Moser's Aniline dyes are powder that dissolve in alcohol. The Stewmac ColorTone's are liquid that dissolve in either water or alcohol.
In order to test the dyes on the wood (maple, in the case of the banjo) I made a dozen strips of curly maple (10x3x0.125 inches) and used them to experiment with the various combinations of color and application. Additionally, I lacquered some of them to get a better read on the final look.
Why alcohol- vs. water-soluble? From what I read at the time I chose to use alcohol-soluble because it wouldn't raise the grain like water-based. After some further experiments after construction I'm not sure it would be that big of an issue. My guess is either will serve the purpose well.