Using iron catalyst to enhance the drying properties of crude tall oil-based wood preservative

Crude tall oil (CTO) is known to be capable of preventing moisture uptake by wood. One problem limiting its use for industrial wood protection is its tendency to exude from the wood. Because of the lack of oxygen, oil polymerization does not occur inside the wood, and the unpolymerized oil may exude from it in time to form a pitch-like surface. The aim of this work was to investigate the potential of iron for catalyzing the CTO oxidation process and to determine the optimum amount of iron catalyst needed. The latter was decided on the basis of differential scanning calorimetry (DSC) measurements and an inclined-plane test. Both methods proved that the drying properties of pure CTO are too low for it to be used as such in wood preservation but its oxidation rate can be greatly enhanced by means of iron catalysts so that oil exudation from the wood can be prevented.