Henry, I followed you here from the citristrip board. I have stripped my slate floor of polyurethane and washed off the stripper (read you in time to not use the wash). Now I think I have all of the stripper off but it looks like a white substnace in the crevices. It could be from the scraping and will be cured by a sealer but maybe I should do something else first? I have read the whole board and did see a reference to alcohol. Will that help? Best sealer? Many thanks for any help you can provide.