Worn hardwood flooring that has seen better days can begin to develop grey areas that become more and more visible as time goes on. Mildew and pet urine can also cause hardwood flooring to turn grey, especially if left on the hardwood flooring for an extended period of time. You can get the grey out of hardwood floors and restore them to their original lustre, using a light application of chlorine bleach and a mild detergent.
Open all of the windows before you begin the stain removal process. Opening the windows will allow for better air circulation when using chemical cleaners. Slip on a pair of thick rubber gloves to protect your hands and goggles to protect your eyes.
Lightly sand the grey areas of hardwood with fine grit sandpaper. The sandpaper will remove the top layer of finish, allowing the stain remover to penetrate the wood.
Fill a 354ml spray bottle with 1 part chlorine bleach to 10 parts water. Add a squirt of dish soap and attach the sprayer to the bottle.
Give the spray bottle a gentle shake to combine the ingredients. Spray the bleach solution onto the grey areas of hardwood flooring.
Watch the area closely as the stain begins to lighten. Rinse the area with a soft cloth and clear water once the grey stain has lightened to match the rest of the hardwood flooring.
Apply a new coat of clear urethane to the newly lightened areas. Apply the clear coat per label instructions. Most clear coat urethanes require application with a soft cloth or paintbrush.
If you do not want to deal with the fumes from chlorine bleach, you can also try using oxygen bleach. Mix the oxygen bleach according to manufacturer's instructions and apply it to the hardwood flooring with a damp sponge. Rinse with clear water after the grey stain has lightened.
Do not over saturate the hardwood flooring with the bleach solution. A light misting is usually all that the wood requires to lighten grey areas. Too much liquid can cause the wood to rot or warp.