Kyllästämistä

Kyllästämistä refers to the process of impregnating wood with chemicals to protect it from decay, fungi, insects, and weathering. This treatment extends the lifespan of the wood significantly, making it suitable for outdoor applications where it would otherwise degrade rapidly. Common uses for treated wood include decking, fencing, outdoor furniture, and structural elements in contact with the ground.

The chemicals used in kyllästämistä, often referred to as preservatives, work by penetrating the wood fibers and making them toxic or repellent to biological threats. Historically, creosote was a widely used preservative, particularly for railway ties and utility poles, known for its effectiveness but also its strong odor and environmental concerns. Modern treatments often involve water-based solutions containing copper compounds, such as copper azole or alkaline copper quaternary (ACQ), which are generally considered safer for the environment and human contact, though still requiring appropriate handling.

The impregnation process typically involves placing the wood into a sealed cylinder where a vacuum is created. This draws out moisture and air from the wood cells. Then, the preservative solution is introduced under pressure, forcing it deep into the wood structure. After the pressure is released and excess preservative is removed, the wood is left with enhanced durability. The color of the wood often changes after treatment, typically to a greenish or brownish hue, depending on the specific chemicals used. Kyllästetty wood is a common and cost-effective material for many outdoor construction projects.