I have used this solution on my antique clocks and it has never failed me. It will clean of years of dirt, grime, oil lamp residue, smoke, etc. but not remove the Shellac. I mix in a small coffee can Half hot water, half MEK (get at hardware store) two teaspoons of boiled linseed oil, and one teaspoon of clear dish washing detergent. Use this mixture in garage or outside well ventilated. I use a 6 Ought steel pad to lightly brush in compound, then wipe clean with water and apply a good furniture polish. It has served me well for 40 years on my clocks and old guns.Inherited old Grand Piano from grandmother, thought was black, used this stuff and it is actually Brazilian Rosewood. Good luck on your project.