comparison of the treatability of southern yellow pine to five Appalachian hardwoods

The preservative treatment variability of many hardwood species is one of the key stumbling blocks to their wider use in high biodeterioration situations, except for railway ties treated with creosote. The home-use or do-it-yourself market is dominated by southern yellow pine treated with chromated copper arsenate (CCA). Recent work performed to determine the treatability of Appalachian hardwoods with CCA, ammoniacal copper quaternary compound, Type B (ACQ-B), creosote, and borates allowed for some direct comparison of the hardwoods (red oak, beech, hickory, yellow-poplar, and red maple) to southern yellow pine. The treatability of southern yellow pine sapwood with CCA was as good or better, when compared to yellow-poplar and red maple sapwood treated with CCA. Southern yellow pine heartwood was consistently in the middle range of treatability when compared to the heartwood of the five hardwoods. Creosote treatment results reaffirmed the well-accepted treatability of hardwoods and explains the dominance in certain industrial markets. Although treatment of hardwoods with CCA, ACQ, and borates was better than southern pine for some hardwoods, the level of penetration and retention, overall, was not sufficient to meet any existing standards.