Touch-up might not fix stained hardwoods

Q. My hardwood floor has a number of dark stains, apparently caused by water. Can I remove the stains or can I give the floor a darker color to hide them?

A. Dark stains on wood floors generally mean that moisture, often water or pet urine, has penetrated the finish and soaked into the wood.

The stains can sometimes be removed and the floor touched up, but if there are a number of stains the best bet is to sand the entire floor to remove the old finish and stained wood, then refinish. Trying to hide the stains with a darker color will only worsen the problem.

If you want to try and remove the stains, you’ll need a suitable wood bleach. The preferred bleach contains oxalic acid and is sold at some hardware stores and home centers, or you can buy it online (use a search engine and the words Oxalic Acid Bleach).

Remove old finish from the stained area with 150-grit sandpaper or steel wool. When you have exposed bare wood, apply the bleach, following directions and cautions on the container. If done correctly, this should remove the dark stains.

Let the floor dry thoroughly and proceed to the most difficult part: trying to match the existing finish. How you do this depends on what type of finish the flooring has.

Many floors are finished with polyurethane, which forms a surface film, and many others have penetrating oil and wax finish. Older floors might be finished with shellac. If you know what the finish is, buy a small can of it, along with a high-quality paint brush.

Try touching up the treated spots so they blend with the rest of the floor. It is unlikely that you will be able to make a perfect match and in the end you might want to sand and refinish the entire floor. If you decide to sand, make sure the wood is thick enough not to be damaged.

Deep sanding requires large tools that are difficult to handle. The tools can be rented, but it is usually best to hire an experienced floor refinisher.

Q. I came across a tip on the Internet stating that it is possible to conserve water (and save money) by partially closing shut-off valves in the house to reduce the flow of water to faucets. Does this make sense? Where are these valves and should they be kept fully open or fully closed?

A. Shut-off valves, also called supply stop valves, should be located in water lines leading to fixtures such as sinks and toilets and to outside faucets.

I don’t advise partially closing any of them to conserve water. These are normally simple valves and their purpose is to provide a convenient way to shut off water for maintenance or replacement of a given fixture, or to stop water flow in an emergency, without turning off the entire household water supply.

You should find shut-off valves under sinks and in the water lines under toilets. Huskier valves are usually used in pipes leading to outside faucets.

All these valves should be kept fully open when the fixtures or faucets are being used, but it pays to close and re-open them at least once a year to help keep them from binding. I’ve seen many neglected valves that have to be closed or opened with pliers or a wrench.

Water flow can be controlled at faucets, of course, and there are a number of legitimate water-conserving methods that you might already know.

Just a few: Take quick showers instead of baths using low-flow shower heads; install water-saving toilets using 1.6 gallons or less of water per flush; put full loads in washing machines and dishwashers; repair plumbing leaks, especially in toilets and faucets; use aerators in faucets.

Q. I have several cans of leftover latex paint that I haven’t been able to use or give away. The toxic-waste people don’t want it. How do I get rid of it safely?

A. Take the lids off the cans and put them in a place where they can’t be reached by children or pets. The solvents will eventually evaporate and the residue will dry up. You can safely put the dried-out paint in the trash. Oil-based paints will generally be accepted in toxic-waste collections.