Bleaching in Furniture Restoration
by Alan Noel
Professional Wood Finisher
Bleaching is a tool that is used sparingly when restoring an old piece of furniture. Often
there will be iron stains from old nails, black or very dark water stains or sun bleached
areas that are far lighter than the surrounding areas, caused by an object being in the same
location for a long period of time. Other cases where bleaching may be used include trying to deal
with a mistake such as using the wrong color stain to begin with or inconsistent coloration of the
lumber being used in a project. That being said, the options for bleaching are few. The options are:
oxalic acid, chlorine bleach and a two part bleach, otherwise known as A-B bleach. Here are some
tips on the different types and how to use them.
- Oxalic acid is used for fading iron and water stains from the surface and is quite
effective. In a glass jar, mix the acid crystals into hot water by stirring in the crystals
slowly until they begin to gather on the bottom. This is a saturated mixture and ready for use.
Wearing rubber gloves, eye protection and a respirator, completely cover the entire surface to
be bleached with the mixture. Spot bleaching is not recommended. The results can be seen after
the bleach has dried. The oxalic acid will appear in crystal form on the surface and has to be
neutralized with clean water until no crystals reappear after drying. Be sure to sand bleached
areas in good ventilation and to wear eye protection and a respirator. Repeat as necessary.
- Chlorine or household bleach is used to lighten most dye stains. For a more effective
chlorine bleach purchase some calcium hypochlorite from a pool supplier and mix the same as
oxalic acid. With proper safety in mind, apply to the entire surface and let dry. Repeat if
necessary. Again, spot beaching is not recommended and be sure to wash with clean water and let
- Two part or A-B bleach is comprised of sodium hydroxide and hydrogen peroxide and is most
effective at removing the natural coloration of woods. Two part bleach will help to eliminate
some pigmented stains but isn't very effective on dye stains. Some say to apply Part A first
and then apply Part B or mix them both before application. I personally can't see any difference
in the results either way.
- As with all bleaches, safety comes first and be sure to rinse well with water. Distilled
water is best.
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Coloring Wood, September 28, 2011
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