What are they?
Where do they come from?
What can I do to remove the black spots?
Some wood species are rich in natural ingredients that migrate with moisture.
Oak (or Chestnut) commonly contain tannins that could potentially stain the surface with the moisture. Thankfully, the leaking tannins are not a permanent issue with Oak and over time they will deplete and no longer present as a dark stain upon the surface.
Often, if the stains are caught early enough and appear as small spots on an Osmo coating, they can be wiped away with a damp cloth before they develop further.
Choosing a transparent Osmo finish with some colour or tint can often be a practical option as the colour/tint will help to mask some of the expected tannin stains.
We recommend using one of two products to achieve this colourful desire protection. Osmo UV-Protection Oil Tints or Natural Oil Woodstain both offer colour and transparency, allowing the wood grain to remain visible through the Osmo finish.
Please contact the expert Osmo UK team for further advice.