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Oxalic Acid Crystals

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In stock
(£13.82 inc VAT)

Oxalic Acid is used to remove dark / black stains, water marks & to refresh the woods colour especially oak, can also be used to remove ink stains, it is also an effective rust stain remover from concrete & metal, supplied in crystal form to be mixed with Water or Methylated Spirits to make an effective wood bleacher,

  • Remove Black / Dark stains on timber, i.e. Kitchen Worktops / External oak structures / Wooden doors / Wooden floors and much more!
  • Remove Tannin Stains
  • Rust Stain removal
  • Water mark removal
  • 99% + purity grade
  • Available in 1Kg, 5Kg, 10Kg & 25Kg
Delivery (Free UK Mainland for orders of £60 and over)

Mainland UK postage rates (excludes London Congestion Charge Zone)

Order Value Below £60    £60 & Over
UK 2-5 Working Days    £5.90         FREE
Next Working Day    £7.90         £3.90
Pre 12 Midday    £10.60         £6.60
Pre 10am    £13.95         £9.95
Saturday    £22.40         £18.40

Cut-off point for next working day is 2:30pm

Click here for full postage details

We also offer a click and collect service for those who would like to order online and collect from our store here in Bidford-upon-Avon. Please select click and collect at the checkout for this service.

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Dark / Black Spots, tannin stains & discolouration of the wood surface are usually caused by moisture and is exacerbated when the moisture is contaminated with metal, such as iron and steel (especially on Oak & Idigbo). This discolouration can be removed with oxalic acid.

Oxalic Acid can also be used to freshen wood colour if it has become lightly grayed due to external exposure to sun light. In the refinishing of wood furniture, oxalic acid can be used after stripping to lighten and soften darker stained areas before refinishing. It can also be used as a rust remover and a stain remover in many other applications.

Just hearing the word "acid" sounds ominous, but oxalic acid is easy and safe to use in the home. In fact it is found in many vegetables including spinach, and rhubarb and is also used in shampoo and washing powders.

Oxalic Acid is supplied in crystal form and looks just like sugar.

Our Oxalic Acid is a high commercial 99% + purity grade Not all Oxalic Acid for sale is the same purity.


Simply mix with water in a clean container until you have a saturated solution (where there is a tiny bit of undisolved sediment at the bottom).
Approx. 60 grams per litre of water. You then have a ready to use solution. Adding more Oxalic Acid crystals will not make the solution any stronger.

Methylated Spirits can also be used as an alternative to water. Using Methylated spirits allows for quicker drying, enabling a protective coating to be applied to the timber sooner. Do not breath the fumes.

Apply the solution directly onto the timber with a brush.

The bleaching process will continue for 1 - 2 hours, however results can often be seen within 20-30 minutes. Multiple applications may be required to fully remove the staining. Once removed, the timber will need to be thoroughly cleaned with clean water or methylated spirits and then allowed to dry.


One kilogram of Oxalic Acid will make approx 15-17 litres of ready to use solution.

Coverage is approx. 12sq meters per litre of solution (depending on porosity of the timber)

A pre mixed Oxalic Acid Wood Bleacher is also available as a ready to use solution in 150ml, 250ml, 1L, 2.5L & 5L bottles.

Please note that any surface coating such as a woodstain, paint, oil etc will prevent the oxalic acid solution from working, so all protective coatings will have to be removed prior to application.

Warning: Oxalic Acid is still an acid and should be treated with respect. In its purified form, oxalic acid is a highly corrosive and toxic substance. Latex gloves should be worn at all times when using it and it should always be mixed and used in a well-ventilated area.

Always protect your skin and wear a dust mask when mixing.

Container size: 1Kg, 5kg, 10Kg and 25kg.

Health & Safety Sheet (Oxalic_Acid_COSHH_Data_Sheet_PDF.pdf, 135 Kb) [Download]

Data Sheet (more_info_oxalic.html, 3 Kb) [Download]

Excellent product, works very well on removing stains and bleaching oak back to its original look .
Well packaged and delivered prompt.
Removed all stains perfectly from our new green oak fixed garden bench, which had many unsightly black stains.
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