Under what circumstances does the effectiveness of wood preservatives diminish or become ineffective?

Wood preservatives are an important tool for protecting wood from corrosion, fungi, insects and moisture. However, the effectiveness of wood preservatives is not always stable under all conditions, and their protective function may gradually weaken or fail as the use time increases or the external environment changes.
The effectiveness of wood preservatives is greatly affected by the external environment. When wood is exposed to extreme weather conditions, especially high humidity, high temperature or strong ultraviolet light, the protective effect of preservatives may decline rapidly. Ultraviolet light is an important factor that causes many preservatives to degrade. When exposed to sunlight for a long time, ultraviolet light will cause the chemical components in the preservative to react and gradually decompose and lose their effectiveness. With strong ultraviolet light, the surface of the wood will fade, crack or even fall off. At this time, the protective effect of the preservative is greatly reduced, and the wood is vulnerable to external corrosion factors.
The effectiveness of wood preservatives will also vary depending on the nature of the wood itself and how it is treated. Some woods, such as pine or willow, have high water absorption, which means that they easily absorb preservatives, but are also susceptible to moisture erosion. If the wood does not fully absorb the preservative during the treatment process, or the preservative does not penetrate deeply into the wood, the effectiveness of the preservative will be greatly reduced. In addition, the smoothness of the wood surface may also affect the adhesion of the preservative. The smooth wood surface may make it difficult for the preservative to penetrate, thus affecting its protective function.
The environment in which the wood is used also greatly determines the effectiveness of the preservative. If the wood is near water or in a high humidity environment for a long time, moisture may gradually penetrate into the wood, causing the wood to swell and deform. This situation easily destroys the protective layer of the preservative, resulting in the failure of the preservative effect. In this environment, the wood is not only prone to rot, but also may breed mold or other harmful microorganisms.
The type and quality of wood preservatives are also important factors affecting their effectiveness. Some preservatives may lose their antiseptic function after a period of use due to unstable chemical composition or poor quality. If the preservative formula contains volatile ingredients or chemicals that are not resistant to high temperatures, they may be affected by moisture in the air or temperature changes over time, causing the preservative to gradually weaken. In some inferior preservatives, unqualified raw materials are used. Although the initial effect may be more obvious, as the use time continues, the anti-corrosion effect will quickly decrease, and even there will be a phenomenon of no protective effect on the wood.
Improper maintenance of wood is also one of the reasons for the failure of preservatives. If the wood preservative is not properly protected after coating, such as failure to effectively avoid external pollution, inadequate cleaning or failure to conduct regular inspections, the anti-corrosion layer may be worn or contaminated, resulting in the gradual loss of protective function. Especially when a large amount of dust, oil or other chemicals accumulate on the surface of the wood, the adhesion of the preservative will be affected, and the anti-corrosion effect will naturally be reduced.