Mix the oxalic acid according to the manufacturer’s instructions. Oxalic acid, a bleach product for wood, comes in crystal form and the user mixes it with hot water. A disposable glass jar, like a clean pickle jar, is ideal to mix the oxalic acid and hot water. Wear rubber gloves, long sleeves and goggles while working with oxalic acid.
Pour a small amount of the oxalic acid mixture on the center of the stain and use a scrub brush to work the oxalic acid into the stain. Leave the oxalic acid on the wood stain according to the manufacturer’s instructions.
Use a rag to wipe off a small portion of the area at the end of the suggested duration to see if the bleach has sufficiently lightened the area. If not, reapply or redistribute the oxalic acid mixture to the wiped area and wait another minute.
Dampen a rag and rinse the bleached stain. Rinse the rag and continue to wipe the stain to remove all residue. Wipe the area with a dry rag.
Allow the bleached area to dry for at least one day before sanding and applying a new finish.
Things You Will Need
- Oxalic acid
- Hot water
- Glass jar
- Rubber gloves
- Protective clothing
- Scrub brush
- Oxalic acid is available at home improvement or paint stores.
- If the bleached area becomes grayish-white, rub very fine steel wool over the stain to lift the light discoloration.
- Using oxalic acid to bleach wood stains is a better choice than household bleach, which can give the wood a greenish-yellow tint.