Removal Of Stains and Tannins in Oak

From the Oak Tree is just in its infancy in comparison to Hortus Ligneous Ltd our oak framing, carpentry and joinery company. We deal with many renovation and restoration projects over at Hortus Ligneous and are often find ourselves making oak "good" again.

I just thought my friends at From The Oak Tree may be interested to know one of the only things apart from sanding that can improve the look and remove those unsightly stains often found in aged oak.  Once the tannins ( a combination of sap and chemicals in the timber that seeps out) and iron come into contact a reaction occurs and forms a blue-balk stain on the oak.


Water, tide marks and Iron stains can be removed by scrubbing the stained area with a solution of oxalic acid in water. Dissolve 1kg oxalic acid to 6Lt of warm water. Scrub stained area using a stiff-bristle brush. Thoroughly rinse with water after treatment. When completely dry, lightly sand the surface. Surface must be clean and completely dry (not just surface dry) before refinishing.

Use an oil or  wood stain for a perfect finish.


To restore the natural oak tones of the wood use 75-125g of oxalic acid per 5lt of hot water then apply by spray, brush or wipe on. 

NB: Oxalic acid is an ACID and therefore the correct protective equipment should be used- should your skin or eye come into attention SEEK MEDICAL ATTENTION URGENTLY.


Get scrubbing...and don't forget your PPE!!

Oxalic Acid



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