Oxalic Acid by Ardec

4.3/5 · 14 reviews
900 g
In stock
Free Delivery
on orders over $90
Quebec, Ontario · More info

Oxalic Acid, also called salt of sorrel, is a very good brightener for wood grayed by rain and U.V. rays. Oxalic Acid can remove tough stains and marks on most woods.

Oxalic Acid can be also used to clean and unclog oiled wood like Teak wood. Oxalic Acid is used to clean wood before the use of natural paints.

Directions for use


In a plastic or glass recipient, add 1 liter of lukewarm water and 75 to 100 grams of Oxalic Acid. Mix well with a wooden spoon. Do not use tools or recipients in metal.


Once the product is dissolved, with a paintbrush, apply generously on soiled wood. Wait 20 minutes and gently brush using a nylon brush. Repeat as needed. Once the wood as brightened, wash with clear water to neutralize the surface.

The brightening will increase slightly when drying. Neutralize good the surface to slow down the brightening process.

Drying time

24 hours sheltered from sunlight.


CAUTION Poison and irritant. Wear protective glasses and gloves. Keep away from children.


Classification Wood Restoration
Brand Ardec
Size 900 g
Sold Since March 11, 2008

100% pure Oxalic Acid




White crystals

Tools cleaning



How to remove graying from exterior woods using oxalic acid?

Graying is a natural process that affects wood exposed to the outdoors. Over time, due to moisture, UV rays from the sun, and other environmental conditions, the surface of the wood fades and takes on a silvery gray tint. This is primarily caused by the degradation of the wood's natural pigmentation.

Although grayed wood generally retains its structural properties and strength, its appearance can give an impression of aging or neglect. Even wood that has received protective finishes or wood preservatives can eventually become gray. Sun's UV rays tend to gradually break down the protective substances, causing the wood to gray over time.

If you want to restore the wood's original color and eliminate its grayish appearance, using Oxalic Acid (also known as wood bleach) can be a solution. However, it's essential to follow the manufacturer's instructions and take necessary precautions when using this product.

Here's how to proceed for an effective treatment:

  1. Dilute the oxalic acid crystals in warm water. The recommended proportion is 75 to 100 grams per liter of water.
  2. Once the crystals are well dissolved, generously apply the mixture to the wood to be treated using a paintbrush.
  3. Let it sit for at least 20 minutes, then vigorously scrub with a suitable brush such as a patio brush or scrub brush.
  4. Rinse thoroughly with clean water and allow it to dry.
  5. Before applying a new finish, make sure the wood is completely dry, as any residual moisture can hinder proper adhesion.
  6. Once the wood is bleached and dry, apply a protective product to prevent further graying.

Remember to wear appropriate personal protective equipment, such as gloves and goggles, when using oxalic acid as it can be irritating and harmful to the skin and eyes.

With these simple steps, you can restore a fresh and revitalized appearance to your grayed exterior wood!

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Value and results!

Tom Wainright · Aug 17, 2021

Perfect for removing those grey stains in my boat. Easy to mix up exactly how much you need. Quickly shipped too!

review of service

Ron Buckingham · Dec 6, 2016

Very happy with order except extra charges from Canada post which your company is looking after and is keeping me informed of, hopefully to a sucessful conclusion.
Thank you'
Ron Buckingham

Oxalic Acid

Claus Reuter · Oct 29, 2016

Thank you so very much. Excellent service.

Good service

Richard Filipowski · Sep 15, 2016

Product is as ordered but the Attention to packaging show this is a well run operation

oxalic acid

Custom Soda Prep & Paint Driedger, Jim · Mar 19, 2016

mixing directions would be helpful

Oxalic acid

sean moore · Oct 24, 2015

my use of oxalic acid is as one ingredient in a mixture for cleaning watch parts prior to repair and restoration. the results were as expected. very good.

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