woodtreatment

Wood treatment is the process of applying chemical, thermal, or coating methods to wood to improve durability, resistance to decay, insect attack, moisture performance, or appearance. The most common goal is to extend service life for outdoor, ground-contact, or humid environments, though indoor applications also use protective coatings or preservatives.

Preservative treatment impregnates wood with chemical preservatives to resist decay fungi and insects. This is often done by pressure treatment, drawing preservatives into the wood under vacuum and pressure. Common preservatives include alkaline copper quaternary (ACQ), copper azole (CuAz), and micronized copper azole. Borates are used for indoors or dry conditions. Chromated copper arsenate (CCA) was widely used historically but is restricted in many regions due to environmental concerns.

Thermal treatment heats wood in a low-oxygen environment to alter its chemical composition. The process dries and stabilizes the wood, increasing decay and insect resistance and reducing water absorption, without added chemicals. The resulting product, often called thermally modified wood, typically has a darker color and may have reduced mechanical strength in some species.

Surface treatments involve applying coatings such as sealants, stains, varnishes, or paints to reduce moisture uptake, UV degradation, and surface checking. Water repellents and penetrating sealers can improve dimensional stability but do not provide long-term biological protection like preservatives.

Other treatments include flame-retardant impregnations and specialized coatings for industrial or transit applications. Choice of treatment depends on species, intended use, exposure class, and environmental considerations.

Standards and regulation: industry guidelines are set by organizations such as AWPA in North America and EN 335/350 in Europe, specifying exposure classes and treatment requirements. Environmental and disposal considerations address leaching and end-of-life handling.