I think that will depend on what kind of finish you have on your psaltery Bob. I have friends who have rosin that just wont come off outside of refinishing, but they have a very thick layer.
I've used a q tip and finger nail polish remover to get it off the old girls I have. The one psaltery looked like it had black flecks of paint on it, that was really ancient rosin.
thanks for the advice, I've tried meth's on cotton wool but that leaves a lot behind. i'll give yours ago.
I have used regular 80% rubbing alcohol that you find in any department store to clean the rosin dust off the strings and the wood; it will NOT harm the finish, it dissolves built up rosin almost on contact (I use a washcloth with just a few drops of alcohol soaked in it) and it dries very quickly. I have NEVER had a problem using this method and I have never harmed the finish. For hard to reach spots, I use a Q-tip lightly moistened with alcohol for the same purpose. Try it; it works!