One. Does wood treated for corrosion contain formaldehyde?
No.
The anti-corrosion characteristics of anti-corrosion wood are obtained by adding chemical anti-corrosion agents to ordinary wood. The formaldehyde in wood processing comes from wood processing using adhesives, so formaldehyde comes from adhesives rather than anti-corrosion agents.
Two. Is treated wood toxic?
Pressure-treated wood typically comes in two varieties, distinguished by the presence or absence of a preservative.
Non-treated, preservative-free wood, known as deep-carbonized wood or heat-treated wood, is a wood treatment process that involves applying heat to wood in the absence of any chemical agents, resulting in a deep brown aesthetic appearance and providing preservative and anti-biofouling properties. This type of wood has a low moisture content, is resistant to water absorption, is dimensionally stable, completely degreased, has good insulation properties, is easy to construct and apply, and has no special odors. It is ideal for indoor and sauna bathroom applications and is becoming a new trend in bathroom decoration. It is also resistant to rot and insect infestation, and has good high-temperature resistance, making it an ideal material for outdoor swimming pool landscapes.
The use of water-based preservatives that are not intended to dissolve is common. These preservatives are applied to the wood within a closed, vacuum-sealed container, while simultaneously applying pressure to the wood. The preservatives are then infused into the wood fibers, resulting in pressure-treated wood. Common types include CCA-treated wood and ACQ-treated wood.
CCA (Chromated Copper Arsenate) consists primarily of copper, chromium, and arsenic. Chromium and arsenic are heavy metals and are considered hazardous substances. In particular, arsenic, commonly known as "verdigris," is highly toxic. Due to the relatively high leaching rates of CCA preservatives from treated wood, there is a potential hazard to water, the environment, and human health. If CCA-treated wood preservatives come into contact with skin, it should be immediately washed off, especially for children, as this poses a significant risk. Similarly, soil and water near CCA-treated wood may exhibit significantly elevated levels of chromium and arsenic, and these heavy metals can migrate to crops and animals. If these contaminated crops or animals are consumed, the heavy metals can ultimately enter the human body.
ACQ is an abbreviation for quaternary ammonium copper. Its main components are copper oxide and quaternary ammonium salts. Although it does not contain chromium or arsenic, its main drawback is instability and high leaching tendency. Currently, ACQ-treated wood is primarily imported from Nordic countries after being treated locally. For example, ACQ-treated wood from Finland is all ACQ-treated. Therefore, ACQ-treated wood is also known as "Finnish wood." However, it is relatively expensive. The most commonly used wood preservatives are CCA-treated wood.