Repair Unsightly Furniture Stains
Ugly black and white wood stains, rings and hazes can be removed
If a dripping houseplant, wet rag, drinking glass or vase of flowers left a telltale haze, white ring or ugly dark blemish in furniture, despair not. Repair is possible.
It eventually happens to everyone: a moist article leaves behind its unpleasant imprint on a prized buffet or dining table. White stains can usually be coaxed out and made to vanish entirely. Black stains require aggressive treatment, and can often be repaired, although seldom invisibly.
Water is the enemy of wood
White and dark wood stains are fundamentally different. The former are caused by moisture entrapped in the finish, whereas black blemishes occur when minerals in the invading liquid chemically react with substances in the wood.
Finishes and sealers beautify wood and protect it. As they age, finishes thin from wear, become brittle, and develop tiny pores and cracks, similar to the drying of human skin. Lacquers, common on many pre-1970s articles, are prone to this condition, although it can develop with varnish, oil, polyurethane and shellac finishes as well.
Removing white water rings and haze from wood and furniture
Tiny pores in older finishes will admit and trap moisture, resulting in rings, cloudiness, blushes and hazes. A wet rag, resting on a table overnight, may leave behind a white imprint of itself, as dampness migrates into the thin film of the finish and stays. Warm wet objects tend to impart deeper and more opaque white stains. A steaming hot pizza can leave a white impression of the box in a wood finish in minutes!
Home removal remedies, such as spreading mayonnaise over the ring, or polishing with toothpaste—seldom work, and can further damage the finish. Similarly, rubbing with very fine (0000) steel wool may eliminate the white stain, but also remove the finish or at least noticeably dull the sheen.
In a pinch, some white rings can be removed with a paste of salt and vegetable oil. Lightly spread the paste over the ring, let it sit a few minutes, then lightly wipe off. Be careful: salt can't dissolve in oil, so its abrasiveness could scratch a fine finish if undue pressure is applied.
Another occasionally effective DIY remedy: blow a warm (not hot!) hair dryer, or set a heat lamp, over the damaged surface, to gently “open” the finish. This technique—which may take several hours—sometimes enables trapped moisture to escape.
Another approach: some water marks can be removed or hidden with commercial wipe-on products branded under names such as Restor-a-finish, Restorzit and Wood Elixir. These products, which also can hide nicks and scratches and rejuvenate dull finishes, are available in common furniture colors. Use the neutral shade if in doubt.
Failing those approaches, white stains can be usually be eliminated non-invasively by a furniture repair professional in two hours or less, using special blush retarder materials and techniques, at a fraction of the cost and inconvenience of stripping and refinishing. The process is smelly: open windows, round up kids and pets and vacate the premises. Cost: $75 to $200, depending on locale and damage.
Adventurous do it yourselfers: spray a very light coat of aerosol Mohawk blush retarder and let it dry. Do not touch the surface while wet or the finish will be permanently damaged. Retarder is basically slow-drying lacquer thinner that actually "melts" the finish and allows the moisture to escape, often in mere seconds. Caution: retarder is toxic and flammable.
Repairing dark wood stains and blemishes
Liquid-borne minerals—notably iron—penetrate severely worn finishes and react with tannins and substances native to wood, causing unsightly dark staining. Removal requires stripping the remaining finish down to the bare wood, wherein the discoloration lies, and treating chemically. Occasionally, light sanding can eliminate superficial stains. Careful: aggressive abrasion will create a shallow dip in the wood that’s difficult to later hide.
Oxalic acid is effective in removing iron stains, especially from oak. Available as a powder from a good paint store, mix oxalic with distilled, demineralized water and apply with a brush according to package directions. Wear rubber gloves and eye protection, as oxalic is hazardous. When dry, neutralize with a weak solution of baking soda. The acid may remove all color, not just the offending one. Sand lightly, apply matching furniture color stain to blend with the surrounding area, and then a finish with a corresponding sheen (gloss, satin, matte, etc.). The repaired area won’t blend in perfectly. Even seasoned wood repair professionals rarely achieve seamless results when matching sheen and color simultaneously in a conspicuous localized area.
Stubborn stains, especially from pet urine, yield only to a chemical treatment called A/B bleach, the heavy artillery in the stain removal arsenal. It is applied like oxalic acid. Beware: the product contains lye and is extremely toxic and hazardous to eyes, skin and breathing. Follow label directions exactly. If in doubt, turn the project over to a pro. As its name implies, A/B bleach removes all color from the wood, and lightens it.
