In most cases, bleaching is essentially a first-aid measure not a routine part of refinishing. A piece of furniture should be bleached if the surface is marked by stains, black rings, or water spots; if the wood is discolored or blotchy; if the color is uneven; or if an old stain or filler is left after the finish is removed. Old filler is often a problem with oak, walnut, and mahogany. Bleaching can also be used to even the color of a piece of furniture made with two or more woods. It can lighten the darker wood to match the lighter one. In this article, we'll review how to bleach wooden furniture as part of a furniture restoration project.
Before you use bleach on any piece of furniture, make sure the wood is suitable for bleaching. Some woods don't accept bleach well -- cherry and satinwood, for instance, should never be bleached. Some woods, such as bass, cedar, chestnut, elm, redwood, and rosewood, are very difficult to bleach, and some -- notably pine and poplar--are so light that bleaching makes them look lifeless. Birch, maple, and walnut can be bleached, but bleaching destroys their distinctive color. And the rare woods -- mahogany, teak, and the other choice woods -- seldom benefit from bleaching. Common woods that are easy to bleach, and may benefit from it, include ash, beech, gum, and oak.
Choosing a Bleach
Not all bleaching jobs call for the same type of bleach. Depending on the problem you want to correct, you may need a very strong bleaching agent or a relatively mild one. Below are some common bleach options you might want to consider.
Laundry Bleach: This mild bleach can solve most refinishing color problems, from stain or filler not removed in stripping to ink stains and water spots. It works well for blotchy areas and for slight overall lightening, but it won't change the color of the wood drastically. Before you use a stronger bleach on any piece of furniture, try laundry bleach; it usually does the trick.
Oxalic Acid: Oxalic acid, sold in powder or crystal form, is used to remove black water marks from wood. It is also effective in restoring chemically darkened wood to its natural color. You're not likely to encounter this problem unless you have a piece of furniture commercially stripped because lye and ammonia, the chemicals that discolor wood, are not recommended for nonprofessional use. Oxalic acid must be used on the entire surface of the wood, because in most cases it also bleaches out old stain. You may have to bleach the entire piece of furniture to get an even color. Oxalic acid is more effective in lightening open-grained wood than close-grained.
Two-Part Bleaches: The two-part commercial wood bleaches are used to lighten or remove the natural color of wood. If you want a dark old piece to fit in with a roomful of blond furniture, this is the bleach to use. Two-part bleach is very strong and must be used carefully; wear rubber gloves and safety goggles. This type of bleach is also expensive. Several brands are available.
Once you decide what kind of bleach you want to use on your wooden furniture, you are now ready to begin the bleaching process. Learn some effective techniques in the next section.