Preventive protection:

• Aims to prevent insects that destroy wood from settling in wood and objects made of wood.
• Consists of filling the wood pulp, in less or more depth, with different poisonous chemical agents.
• Prevents organisms from settling in wood for a shorter or longer period, depending on the agent used, way of applying it as well as the place where the wood is used.
• The choice of agents and depth of the protection depend on the purpose of wood pulp (whether it is used outdoor or in buildings), as well as whether the wooden objects or constructions are endangered.
• Preventive protection lasts until the moment when the wood pulp is built in or finally processed.

Direct protection:

• Repressive measures against insects are taken when the insects or their larvae are already in wood, so as to destroy them or wipe them out.
• The most reliable are the chemical methods that imply use of gaseous insecticides (fumigants), whose vapors are able to penetrate corridors quickly and destroy insects there. Different liquid chemical agents with insecticides solved in them, able to absorb into wood easily, are also used.

Ways of preventive chemical protection are as follows:

1. Spraying and covering (by spreading);
2. 5-15 minute immersion into cold or hot conserving solutions;
3. Partial protection consists of covering, spreading, immersing or spraying those parts of construction that come into contact with soil, other building material and those that are exposed to atmospheric changes (e.g. telegraphic poles etc.);
4. Injecting into holes;
5. Bandage protection;
6. Impregnation in pools;
7. Impregnation in pools with alternatively hot and cold solutions;
8. Impregnation in living condition;
9. Impregnation by osmosis;
10. Infiltration by Boucherie;
11. Impregnation of wood under pressure;

1. complete
2. partial.

Chemical substances used to preserve wood:

1. Unorganic salts (water soluble agents);
2. Substances of tar (oily substances);
3. Organic synthetic substances (soluble in organic solvents);
4. Mixture of oil and unorganic salts;
5. Emulsions;
6. Artificial resin.