Protecting Polyurethane Finished Floor
Once you put polyurethane on slate tile, you'll have to learn to live with the scratches
Q: I have a slate tile floor with a polyurethane finish. It's very attractive, but it scratches easily. How do I keep the look while protecting my floor?
— Jane, Lexington, Kentucky
Tom Silva replies: Unfortunately, there is no real foolproof method. Probably the only way you're going to keep from scratching it is to wear socks when you walk on it. You can't drag your furniture over it—you have to treat it as if it were a hardwood floor.
Urethane is going to scratch on that type of floor, and even applying more coats of it won't do the trick. In my estimation, most slate floors are better left without a finish on them. However, once slate tiles have been treated with polyurethane, the finish penetrates the pores of the slate and cannot be removed. In your case, I'm afraid you may just have to learn to love the scratches.