there is an abrasive scouring powder on the market at the local grocery stores called "bar keepers friend". Put a little water(a few ounces) down with some sprinkles of bar keepers friend and let it sit for about two minutes. Use a "new" rough side sponge and scrub- not too hard and the spots should come right off. I did not lose any of the finish on my 1952 wood table. I went with the grain and was unbelieviably pleasantly surprised. I finished with some murphy's oil soap and dried it off. good luck