Oxalic Acid Wood Bleach

Safely remove tough surface stains without bleaching the wood

Have you ever removed the finish from a piece of furniture and found black stains or black rings from metal pots? Have you ever removed the finish from a floor and found black or deep brown pet urine stains in the wood, which no amount of sanding will take out? These are all iron stains caused by the chemical reaction of tannic acid in the wood mixing with the trace metals in urine and water.

Oxalic Acid Wood Bleach can remove these types of stains all while not bleaching the wood. The instructions below illustrate how to make a big batch of bleach mixture and mop it on the whole floor. This is not necessary for single spots on the wood. It is suggested that users mix about two tablespoons of Oxalic Acid Wood Bleach in a quart of hot tap water and allow it to dissolve.

When dissolved, use an artist brush and paint it in the mixture on the stained areas only. Allow to dry. The stain will lighten. If it does not disappear, then do another coat. You may need to coat it three or four times, allowing time to dry between coats. Once the stain is gone you can sometimes get a slight halo effect around the area where the stain was bleached. To take care of this, saturate a rag with the oxalic acid solution and wipe a thin coat over the stain and surrounding area. Allow to dry. This should take care of the stains. Once the stains are gone you need to neutralize the acid so it will not react with your wood finish. Mix up two tablespoons of borax in a quart of hot water. Saturate a rag with the borax solution and wipe the floor and allow to dry. Borax is sold in the super market laundry section as Twenty Mule Laundry booster. It is a natural product.

16 oz. makes 2 gallons | $9.99

View the Wikipedia information for oxalic acid.


SURFACE PREPARATION: Wood must be free of all coatings, waxes & oils. Use appropriate strippers and cleaners to remove coatings.

MIXING: ALWAYS WEAR RUBBER GLOVES, EYE PROTECTION & PROTECTIVE CLOTHING WHEN USING THIS PRODUCT. Dissolve contents of this package with one gallon of hot water.


  1. Add entire contents of jar to 2 gallons of water or 2 tablespoons per quart.
  2. Apply hot solution w/scrub brush, old paint brush or mop of large jobs. Apply liberally allowing the solution to remain on surface until bleached to desired lightness.
  3. If solution cools before job is finished, reheat the solution being careful not to allow it to come to a boil.
  4. Rinse treated area repeatedly w/clean water and allow to dry.
  5. Test removal of the bleach from the dried wood by wiping the surface w/dark-colored cloth checking for a powdery residue. If powder is present, rinse again w/clean water and allow to dry.
  6. Wood grain may be raised as a result of application of this product. Ensure all bleach residue is gone & then sand wood & finish w/desired product.


View the Material Safety Data Sheet for this product.

At The Real Milk Paint Company we do our best to provide safe products as well as information. However we cannot guarantee that individuals with compromised immune systems or allergies will not have a reaction to our products. We strongly recommend that each person take their own personal responsibility in testing this product for their own personal use.

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  • Erica

    A dead bird decomposed on my light oak floor when the house was empty. It left a dark, nearly black stain of bodily fluids and a putrid odor. Will oxalic acid work to remove it?

    • http://www.realmilkpaint.com/ Real Milk Paint

      Erica ,
      This would be the best thing I know to try and get it out . You may need to apply and let dry multiple times . It should however do the trick

  • Amy

    I’ve sanded downva piece of wood furniture and want to re-stain it. If I bleach some problem areas first, will the new colored stain take on those spots?

    • http://www.realmilkpaint.com/ Real Milk Paint

      This bleach will only bleach the wood back to its natural color . So it should not leave a white spot if that is what you are thinking ?

  • katee

    Hello. I wanted to inquire if this could remove the black & green stains from accidentally using Easy OFF oven cleaner on my birch wood color hardwood floors? Looks like it ate even the wax too. Please advise. Any suggestions would be appreciated! Thank you!

    • http://www.realmilkpaint.com/ Real Milk Paint

      This should work to bring back the color on those spots . Do a test first on one spot . Paint it in and allow to dry

  • Rose

    We have a 12’x16′ red oak flooring we are trying bleach, how much Oxalic acid will it take?

    • http://www.realmilkpaint.com/ Real Milk Paint

      About two containers will do the trick . This will make 4 gallons

      • Rose

        Our kitchen floor is a white oak, we removed the wall leaving the living room (which is red oak) open to the kitchen, we are bleaching the red oak flooring in hopes it will be close to the white oak,?is this a possibility

        • http://www.realmilkpaint.com/ Real Milk Paint

          This may very well work however if it does not make it light enough try Hydrogen Peroxide . Do a test first with the Hydrogen .

  • http://www.realmilkpaint.com/ Real Milk Paint

    Yes , This would be the product to use

  • bill

    will oxalic acid remove sticker stains in white oak

    • http://www.realmilkpaint.com/ Real Milk Paint

      Hmmm….I have not tried it for that . But I think this would be the best option to try

  • Julie

    Can I use baking soda to neutralize the oxalic acid, or is borax the only good option? I have beech countertops. I don’t know if that’s relevant, but I thought I’d mention it, just in case.

    • http://www.realmilkpaint.com/ Real Milk Paint

      Baking Soda should work as well . Borax however does stay in the wood and can act as a preservative as well

  • Julie

    Is heating necessary for the oxalic acid solution to work well? I have a few tenacious spots that remain black after repeated treatments over the past few days. It has worked amazingly well on all but these few spots. I tried H2O2 prior to the oxalic acid, but it hardly did anything.

    • http://www.realmilkpaint.com/ Real Milk Paint

      Heating may help if you finds crystals in the bottom of your container . Also sand the area a bit when dry to maybe open it up more

  • Lynda Brothers

    I’m looking for a wood bleach that will lighten up the whole panel of wood for post artwork. Will this work for that application?