Preservative treatment of wood by diffusion processes - Simulation of commercial treatment processes

IRG/WP 3498

P Vinden

Spruce (Picea abies), Scots pine (Pinus sylvestris) and birch (Betula pendula) were preservative treated by diffusion with mixtures of copper sulphate and arsenic pentoxide. The preservative was fixed after a suitable diffusion storage period by soaking in ammonia solution. A high standard of treatment could be achieved in spruce sapwood. This was attributed to its low wood density, and high wood moisture content. The variable treatability of spruce heartwood and poor treatability of Scots pine heartwood was related directly to their moisture-content. Complete preservative penetration could be achieved in spruce heartwood when moisture contents were 60% or above whereas Scots pine heartwood with a fresh moisture content of 30% was untreatable by diffusion. Preservative penetration was directly related to preservative retention and immobilisation by fixation. This was demonstrated clearly for birch which because of its high basic wood density tended to immobilise a greater quantity of preservative salt per unit volume. The effects of preservative retention and diffusion storage time on the subsequent distribution of preservative was determined for Pinus ponderosa. The relationships established can be used for defining suitable diffusion treatment schedules.


Keywords: DIFFUSION; DENSITY; PICEA ABIES; PINUS SYLVESTRIS; STORAGE TIME; BETULA PENDULA; COPPER SULPHATE; ARSENIC PENTOXIDE; AMMONIA

Conference: 88-04-24/29 Madrid, Spain


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