Tannin stains on oak wood: Prevention and solutions

Oak wood, valued for its durability, presents the dilemma of tannin stains caused by tannic acid. These stains occur due to moisture and contact with iron/metal. But how can tannin stains be removed? For example, with our OLI-NATURA Tannin-Remover. This video shows how it works.

The popular oak wood in particular contains a high proportion of tannic acid, known as tannins, which occur both in the bark and in the wood of the oak. However, tannic acid is water-soluble and plays a key role in the formation of unsightly water marks and black stains on wooden surfaces.

WHEN DO BLACK STAINS OCCUR?

Black stains occur especially when tannic acid comes into contact with iron or metal particles and water. This can happen, for example, when a metal tin is placed on a damp oak wood surface or iron table legs are placed on freshly mopped oak parquet flooring. Even metal shavings can cause such discoloration. The resulting oxidation reactions lead to permanent, dark discoloration that cannot be easily removed using conventional cleaning methods. Here we provide practical solutions for preventing and treating them.

MEASURES AGAINST TANNIN STAINS:

1. Prevention by Water Popping:
   To prevent the formation of tannin stains, it is recommended to wet oak wood before oiling it. This traditional technique, known as Water Popping, helps wash out some of the tannins. Adding a small amount of intensive or exterior cleaner further reduces the reactivity of the tannins.
   
   
2. Treating existing stains: Not every oak wood table or floor has been pre-treated using the traditional wetting technique, which can result in unwanted stains. In this case, our OLI-NATURA Tannin-Remover, based on oxalic acid, provides a solution. OLI-NATURA Tannin-Remover can simply be dripped onto the affected area. After allowing it to work for a short time, the area should be wiped with a damp cloth and, if necessary, partially re-oiled. Alternatively, the stain can be carefully sanded out and then re-oiled to restore the appearance of the wood.
   
   

STEP BY STEP - Instructions for the Tannin-Remover:

1) Apply a few drops of the Tannin-Remover directly to the stain and leave the product to absorb for about 5 to 10 minutes to achieve the best possible effect.

2) Moisten a cotton cloth with lukewarm water and wipe over the affected area.


3) Allow the area to dry thoroughly. The area may now appear lighter than the rest of the surface.


4) It is therefore important to subsequently treat the area with oil and wax to protect the cleaned surface again.

Which oil or wax is right for me?

If you want to buy a wood oil, the selection may initially seem huge and overwhelming. We will help you make your decision and show you which OLI-NATURA oils & waxes are best suited to you or, rather, to your project. Our experts will quickly and easily recommend a suitable wood oil, answer your product questions and provide application tips. We are happy to assist you with any questions by phone at 037208/84-488 or via email at faq@oli-lacke.de.