Hi. I work in a restaurant, in one half we have dark wood tables and the other half light wood. I am unsure of the finish but I know the dark wood have some kind of seal on them to protect against hot plates and cups and the advise was to use glass cleaner to clean them. I would hazard a guess that the lighter wood have the same seal. We use the shiny birthday/celebration confetti on occasion which has stained. Can barely notice it on the dark tables but it ruins the look of the others. I have tried bicarbonate mixed with lemon juice, which after several minutes reduced the stain on the mark I tried but also stripped the seal off. Any suggestions? Also if we decided to sand it down what would be the best way to restore? Thanks in advance