Autoklaavikäsittely

Autoklaavikäsittely, or autoclave treatment, is a wood preservation method in which timber is impregnated with preservative chemicals inside an autoclave by cycling vacuum and pressure. The goal is to force preservative solution into the wood’s cells to increase its resistance to decay, fungi, insects and, in some cases, improve moisture barrier properties.

The typical process involves loading the timber into an autoclave, creating a vacuum to remove air from the wood’s pores, introducing preservative solution under elevated pressure to drive it deeper into the wood, and maintaining a dwell period to allow diffusion. After impregnation, the pressure is released and any excess preservative is removed, followed by drying and sometimes curing of the treated wood. The exact sequence, temperatures and dwell times vary by product, preservative system and regional regulations.

Preservatives used in autoclave treatment are commonly water-borne or solvent-based chemical formulations designed to remain in the wood for extended periods. Copper-based systems, such as certain copper azole or alkaline copper quat formulations, are frequently employed in modern practice, while older treatments like chromated copper arsenate have been phased out in many markets due to environmental and health concerns. Regulations and standards governing the choice of chemicals, application methods, and post-treatment handling differ by country and region.

Applications of autoklaavikäsittely include outdoor construction timber, fencing, utility poles, and other wood products exposed to soil contact or weathering. Benefits include increased durability, reduced susceptibility to decay and insect attack, and improved dimensional stability. Limitations include higher production costs, potential color changes, leaching risks if improperly sealed, and the need to comply with environmental and worker-safety requirements.