Effect of wood moisture content and rod dosage on boron or fluoride movement through Douglas-fir heartwood

The potential for moisture sorption by boron and fluoride rods following application of rods to wood to affect subsequent chemical diffusion was investigated in small Douglasfir blocks conditioned to 30, 60, or 90 percent target moisture content (MC). MCs tended to decline over the 180-day test period, but there was no evidence that the rods acted to draw moisture away from the wood. As expected, chemical movement tended to increase with increasing MC. Threshold levels were reached within 180 days for boron, even in blocks at 30 percent target MC. Fluoride levels tended to be much lower, reflecting the much lower dosages applied. There was no evidence that rods sorbed enough water to reduce moisture availability for subsequent diffusion. © Forest Products Society 2009