1. Select old pine forests with a tree age of more than 30 years to collect pine bark. These old pine barks are highly chapped and easy to separate and collect, or the fallen pine barks can be collected directly in the wood processing plant.

2. The collected pine bark needs to be removed and broken into pieces with a diameter of about 2 cm, which is convenient for post-treatment and use after decomposition.

3. Put the collected fine pine bark into a larger container and soak it in boiling water.

4. When soaking, the water surface of pine bark needs to be completely submerged. When the water level drops after soaking for a period of time, it is necessary to replenish water in time to make pine bark fully absorb water. At the same time, boiling water can also kill eggs and germs, which is beneficial to the precipitation of some insoluble components in pine bark and can prepare high-quality plant raw materials.

5. Drain the pine bark soaked for 2-3 days, sprinkle a small amount of urea and lime powder, fully stir evenly, pile it up, cover it with plastic film and seal it.

6. You can also put the evenly stirred pine bark into a closed woven bag and pile it together for fermentation.

7. It is best to pile it in a place with strong light and promote decomposition through exposure and high temperature.

8. Generally, after 2~3 months of fermentation, the pine bark changes from brown to dark brown, and the rosin of pine bark disappears and dries.