In the Finnish mechanical and chemical forestry industry, three million tonnes of softwood bark are produced annually, presently mainly used for energy production.
Using a method developed by VTT, a high yield of pure tannins can be extracted from the bark for use as a raw material for resins used in wood products. The residual fibre fraction can be used to produce sugar as a raw material for fermentation products. It is also suitable for material applications.
Traditionally, tannins are extracted from the bark by hot water extraction. In addition to tree species, the extraction yield is influenced by the origin and processing history of the raw material.