Sealer causes problems on reader's slate tiles

Dear Jerry:  I have a contemporary-style house in the town of Greece. It was built in 1986. My question for you is regarding my kitchen and foyer flooring. I have slate tiles approx. ½- ¾-inch thick by 12-inches square.  I think they were put in about 10 years ago.  

The tiles were pretty dull when I moved in. I had a professional floor guy put a glossy sealer put down to really bring out the natural colors of the slate, a couple of years ago.

Shortly after they dried, they started to turn whitish and crusty-looking, I call them pockmarked. Some parts of the slate look pretty and some have whitish circles on them.  I complained and the floor guy came back, and sealed them again, and it just got worse.

My question: Can I save them or do I have to rip them out and put something else down? If they would stay shiny and bring out the color I’d be so happy. The floor constantly looks dirty or like there’s a soap scum on them. I do clean them with water and mild solution.  Is there a way to strip them?

By the way, love your column.  Thank you for any advice you can give me. 

— C.M., Greece   

I think you should try to save the tiles.  Unfortunately, for whatever reason, the sealer is incompatible with the slate.  Therefore you should try to remove it, according to expert mason Marty Naber.  

First, try to find out what sealer the “floor guy” used.  You may have some left over, or you may have to contact him. Once you know the brand and type of sealer, you can contact a tile shop or the company for the proper chemical/solution to use in removing it.  

When you have the remover, use it on a small section first; if things go well you can continue on.  This will likely involve scrubbing and rinsing as you go. Follow the directions carefully.  

When the sealer is gone, then Naber suggested using an infuser product to give the tile a fresh look.  Again, try a small area first to see how it reacts with the tile.  This product should be available at a tile retailer; Naber suggested The Tile Shop on Jefferson Road in Henrietta. They may also be able to help you with suggestions on removing the current sealer.    

Dear Jerry:  We live in older home in Brighton. When taking up an area rug, we noticed a couple of pet stains on the original oak floors.  They are darker than the rest of the floor.  Can they be removed or do we need to get the whole floor professionally sanded and refinished? 

— No No Bad Dog, Brighton  

You can certainly try to clean up the stained area.  First, lightly sand the area. A random orbital sander will make this easier.  Use a fine sandpaper and clean the existing finish of the area, going slightly beyond the stained parts. Go easy with the sander; you don’t want to grind down the wood. Simply sand enough to remove the finish. 

Once sanded, you can use oxalic acid to start bleaching or lightening the wood.  This is a powder you mix with water.  Start with a mild solution and work up to a stronger concentration.  You wipe or brush this on the stained area, and let it dry prior to a second application.  I’d wait at least a day between coats or longer if the floors is still damp.  Eventually, the stained area will lighten and become almost white; lighter than the surrounding wood.  This is what you want. 

When the floor does lighten up, carefully rinse off the acid and allow the area to dry thoroughly.  Now, you are ready to match the light area with the rest of the floor. Ray Case, of Ray Case Floors, suggested using a wiping stain such as Old Masters or Zar (available at Mayer Hardware).  

Choose a light-color stain such as maple or oak or a combination of the two.  (A photo of your existing floor may help at the paint store.)  Thoroughly mix the stain and brush it on the bleached area.  After a few minutes, wipe off the area with an old rag. This may take a bit of trial and error, but eventually you’ll make a match with the existing finish.  If your first attempt is too dark, then use paint thinner to remove some of the stain.  If it is too light, apply another coat.  

When the stain is dry, apply at least two coats of varnish or polyurethane, either gloss or satin, to match the sheen on the existing floor. 

If the finish is too shiny, rub the finish slightly with fine steel wool.  

Jerry Ludwig is a former contractor and home inspector.  He is an honorary member of the American Institute of Architects.  Email your house questions to jludwig@rochester.rr.com or write him at P.O. Box 25510, Rochester, NY 14625. Please include the year your house was built and the town where you live.