Woodsman,
I've had good success using Pilkington's spirit base stains for darkening & adding a little color to finished stocks that are too light for my taste. The stain will penetrate most finishes I've tried it on with the exception of some urethane modified oil finishes. I usually mix the Pre 64 & English Red stains together to get the correct color. A little experimentation normally required & the stain can be mostly removed with the special thinner they sell w/ the stain if you don't like the results.
It will soften some finishes on initial application but the finish will reharden after it dries. I wipe it on with a piece of cotton flannel.
Pilkington stains are available from Midway & Brownells.
