Wood bluing(blue stain) is usually due to the invasion of fungi in the wood, causing blue spots to appear on the surface of the wood.
Here are some suggestions for dealing with blue stain:
1. Removing Affected Areas: Affected blue wood can be removed by sanding the surface of the plank to ensure that the blue stain is completely gone. Sand carefully along the grain of the wood to avoid additional damage to the board.

2. Disinfection treatment: Disinfecting the surface of the wood board can kill the residual fungus on the wood. Choose a suitable disinfectant, dilute it according to the instructions, and apply it evenly on the surface of the board with a brush or cloth. Wait for a while to ensure that the sanitizer is fully effective, then rinse the veneer with clean water.

3. Anti-fungal treatment: In order to prevent the board from being attacked by fungi again, it is recommended to use a special wood preservative for treatment. Apply preservative to the entire surface of the board as directed, ensuring even coverage. This will protect the board to a certain extent and prevent fungal growth.

4. Painted or Oiled: It is recommended to paint or oil the panels after the anti-mildew treatment has been completed. Choose a paint or oil that matches the board material and apply to restore its beauty and protective properties. Multiple coats can be applied as desired for extra protection.

5. Moisture resistance: High ambient humidity is the main cause of wood bluing. It is critical to maintain a dry environment where the board is located to prevent moisture. This can be achieved by using dehumidifiers, ventilators, etc. to control indoor humidity, maintain wood quality and prevent fungal growth.

6. Regular inspection: Regularly check whether the veneer has any signs of blue, which will help to find problems in time and take appropriate measures. This will prevent further deterioration and protect the quality and appearance of the board.