Relative resistance of various hardwoods to injection with creosote /

Abstract

For a description of the wood of the conifers see Bulletin 101 of the Department of Agriculture. RESISTANCE OE HARDWOODS TO CREOSOTE. 3 wood. These rings are more or less conspicuous in the hardwoods of temperate regions, especially in those of the ring-porous group. In general, the springwood is more open and has fewer thick-walled cells than the summerwood. Medullary rays.-The medullary rays (silver grain) which extend like the spokes in a wheel from the bark toward the pith at the center of the tree, are very conspicuous in some hardwoods, such as oak, beech, and sycamore.. MICROSCOPIC STRUCTURE. The microscopic structure of the hardwoods is illustrated b}^Plates I, II, III, and IV. Plate I is a photograph, taken through the microscope, of a section of maple. This wood belongs to the diffuse-porous group of hardwoods, which is so called because the pores or vessels (V) are scattered with considerable uniformity throughout the annual ring (AE). In this group the pores in the springwood (SP) are generally but little larger than those in the summerwood (SW). Plate II shows red oak, an example of ring-porous wood. In the springwood of this species there is a noticeable group of large pores. When seen on the cross-section of a log these make conspicuous concentric rings around the pith. In this wood the pores are not distributed uniformly through the annual ring and there is a very considerable difference in the sizes of those in the springwood and the summerwood. The springwood pores in a ring-porous wood are usually considerably larger than the corresponding pores in a diffuseporous wood. Although these two species are typical of the two groups, yet in each group it is possible to find variations from the types of structure shown. Some diffuse-porous woods, for example, are more porous than maple ; that is, t\\Qj have more pores per square inch in proportion to the number of fibers and the like than others do. Some of the ring-porous woods have the large springwood vessels blocked with cell-like growths called tyloses 1 (T, Plate IV). These are visible to the naked eye as glistening fragments in the pores of such woods as white oak or hickory. T3 r loses are also present in the diffuse-porous woods, although somewhat less abundantly and uniformly developed. They occur in the vessels which are not active in the transfer of sap ; therefore, they .are most numerous and completely developed in the older sapwood and the heartwood. Medullary rays.-The medullary rays (ME) are generally rather conspicuous in the hardwoods, although in woods like aspen and 1 " Tyloses : Their occurrence and practical significance in some American woods,"

Evaluation of Wood Species and Preservatives for Use in Wisconsin Highway Sign Posts

“…The limited research available on preservative treatment of elm species indicates that they are at least moderately treatable. Teesdale and Maclean (1918) grouped American and slippery elm with the most treatable species for pressure treatment with creosote, and classified rock elm as moderately treatable. American elm was also among the most treatable hardwood species for pressure or thermal treatment with pentachlorophenol, but only moderately treatable by coldsoaking with pentachlorophenol or water-based solutions (Koch 1985).…”

“…However, the little information that is available does indicate that ash is somewhat treatable. Early researchers at FPL conducted creosote treatments of 25 hardwood species and grouped them into three categories based on extent of creosote penetration (Teesdale and MacLean 1918). Both green and white ash were placed into the most treatable category.…”

“…The research that is available generally indicates that basswood is treatable, at least when pressure-treated. Teesdale and MacLean (1918) included basswood among the most treatable of three groups of hardwoods when pressure-treated with creosote, and a high retention was achieved when round basswood fence posts were pressuretreated with creosote (Gjovik and Davidson 1975). Tesoro et al (1966) also found that creosote penetration in basswood heartwood was among the highest of the mixed hardwood and sapwood species he evaluated.…”

“…Teesdale and Maclean (1918) evaluated the treatability of sugar maple with creosote and placed it in the "intermediate" category. FPL researchers treated 19-by 19-mm (¾-by ¾-in.)…”

“…Neither paper nor yellow birch (B. alleghaniensis) is naturally durable, and historically there has been little interest in preservative treatment of birch, and particularly paper birch, because of its value in other applications. Teesdale and MacLean (1918) did evaluate the treatability of yellow birch with creosote and placed it into the most treatable group of the species they evaluated. More recently, FPL researchers pressure-treated yellow birch heartwood stakes (19 by 19 by 457 mm) with either CCA or ACQ as part of a larger durability evaluation.…”