There are several different ways to remove water marks from wood, and the approach that works best often depends on the extent of the damage. Surface marks can often be removed by applying dry heat to the area or rubbing the stain gently with mayonnaise or toothpaste. Deeper staining may require removing the finish, treating the wood, and then refinishing it. In all cases, do some research on the wood and its proper care before trying any treatment to avoid causing permanent damage.
Causes
There are two main types of marks caused by water on wood: white or cloudy marks and dark stains. White marks are made when water gets into the finish on the wood and cracks or clouds it. Darker marks and stains often occur where the water has seeped past the finish and gotten into the wood itself. Both types of marks can be caused by a beverage glass or a hot, damp item — like a pizza box or a casserole dish — placed on a table. Surface damage is usually relatively easy to treat, especially it if it done soon after it occurs, but deep staining typically requires more extensive repair.
Preparing to Remove Water Marks
Before using any treatment to remove water marks, do some research. Some woods and finishes respond better to certain treatments, and you could further damage a surface by using an inappropriate stain removal method. If possible, read any information that you might have from the manufacturer of your furniture or call its customer service department for suggestions. If you are unable to get professional advice, try the treatment on a small area of the floor or furniture to see if it adversely affects the finish.
You should also remove any polish or wax from the surface before you treat it. These are used to improve the appearance of wood as well as to protect it; since it's designed to help repel water, it may prevent anything used to treat the water mark from penetrating as well. Wax or polish can be removed with wood cleaner or a remover specifically designed for these substances. Always read and follow the directions carefully, and test any cleaner in a small area first to see how the wood reacts.
Removing White Marks
Dry heat can help get rid of recently developed white rings by helping to evaporate any trapped moisture. Try using a blow dryer set on low, and hold it above the stain, constantly moving it around to prevent heat damage. You can also cover the area with a soft, lint-free cloth and press it with an iron set on medium-low; keep the temperature down and check under the cloth every 30 seconds or so to see if the mark is still there. A small lamp can also be held over the area, as the bulb can usually generate enough heat to serve the same purpose. In addition to removing any trapped water, using low, dry heat may help any cracks in the finish fuse back together.
If you're concerned about damaging the surface with heat, you can try an oil-based treatment instead. Apply some mayonnaise, petroleum jelly, lemon oil, or even cooking oil to the area and rub it with a chamois, cloth diaper, or soft rag that won’t further damage the finish. You can leave these substances on particularly stubborn white rings for several hours. It is thought that they will soak into the finish, replacing the water and reducing the appearance of the mark.
Other experts advise using toothpaste (not gel) to rub away white rings caused by water damage. This can act as a gentle abrasive to remove water marks. You can also combine mayonnaise or another oil-based solvent with baking powder or cigarette ash and use it with a soft cloth to buff the stains away. Some experts recommend using lemon or another oil and very fine steel wool instead of a cloth. The problem with abrasive methods, however, is that you increase the risk of damaging the wood, so use caution and test the method first before abrasively cleaning a large area.
Unfortunately, these remedies can affect the appearance of your floors and furniture, and the treatment may scratch or dull the wood's surface. If you are working with very old, expensive, or fragile wood, it may be best to seek professional assistance rather than attempting to remove water marks on your own. Wood coated with a high quality lacquer, for example, can be treated with a special retarding spray, but it should only be done by a professional.
Removing Dark Marks
To remove a dark water stain, you first need to strip the finish from the wood and treat the area directly. Oxalic acid, a compound used in wood restoration, is often recommended because it typically does not change the color of the wood itself. Also known as wood bleach, you may need to apply several coats to the surface until the stain fades away. Bleach typically needs to be neutralized as well, so it should be rinsed with water and a mix of water and baking soda. After treatment, you, or a professional, can refinish the surface.
Completely refinishing a floor that has a dark mark can add value to a home, but that's not always true for furniture items. In many cases, antiques should not be refinished or they will be worth less. It's best to consult with an expert about whether it's worthwhile to try to remove water marks from antique wood, and if so, you may want a professional to do the restoration.
Protecting Wood Furniture and Floors
You can help protect wood from water damage by creating a barrier between the wood and liquids. Always use coasters under drinks and trivets under hot food containers. You can also protect a table by covering it with a glass tabletop. Regularly apply furniture or floor wax to keep the surface protected. You may also want to consider furniture treated with a synthetic resin finish that is resistant to stains and other damage.
