Method 1. Antiseptic wood processing soaking method
Under normal temperature and pressure, the wood is immersed in the tank or pool containing preservative solution, and the wood is always below the liquid level. The soaking time depends on the tree species, wood specifications, moisture content and pesticide type, and the specified retention amount and permeability of chemicals shall prevail. In order to improve the treatment effect, ultrasonic wave, heating device and surfactant can be set in the soaking solution to improve the permeability of wood. Depending on the length of soaking time, the immersion method can be divided into instantaneous immersion (time from seconds to minutes), short-term immersion (minutes to hours) and long-term immersion (time from several hours to one month). Suitable for veneer and remedial preservative treatment, as well as temporary wood.
Method 2. Antiseptic wood processing diffusion method
According to the principle of molecular diffusion, with the help of water in wood as the carrier of drug diffusion, the agent diffuses from high concentration to low concentration and spreads to the deep layer of wood. Therefore, the following conditions must be met in the treatment of wood by diffusion method:
1. The moisture content of small wood is high enough, usually more than 35% - 40%, and the green wood is good;
2. Water borne agent (diffusion type) has high solubility and slow solidification;
3. The ambient temperature and humidity are high. According to the operation process, the diffusion method can be divided into paste expansion method, immersion or spray diffusion method, bandage diffusion method, drilling diffusion method (or spot diffusion method) and double agent diffusion method. The equipment investment of diffusion method is less, and the production process is simple. It is easy to be applied and popularized in rural areas. Similar to this method is the replacement of tree sap.
Method 3: antiseptic wood processing - hot and cold trough
Based on the principle of thermal expansion and cold contraction, the gas in wood will expand and contract in hot liquid, resulting in pressure difference, so as to overcome the resistance of liquid penetration, that is, wood is heated in hot liquid. It makes the air in the small timber expand and part of the water evaporates. The internal pressure of the wood is higher than the atmospheric pressure, and the air and water vapor overflow to the outside. At this time, the wood is quickly placed in a relatively cold liquid, and the wood suddenly cools. The air inside the wood is under negative pressure due to shrinkage, and the cold liquid seeps into the wood. According to the treatment method and the configuration of cold bath, it can be divided into two tank alternating method, single tank hot and cold liquid alternating method and single tank placing cooling method. Due to the low treatment efficiency (compared with the pressure method), the energy consumption per unit product is high, so it is widely used in small batch wood preservative treatment.