United States Department of Agriculture Treatability of Native Forest Service Forest Softwood Species of Products Laboratory Research the Northeastern Paper FPL-RP-508 United States Lee R. Gjovik David R. Schumann Abstract Several softwood species of the northeastern United States could have greater commercial value if they could be treated with preservatives. Balsam fir, east- ern spruce, and eastern hemlock are candidate species. However, these species are susceptible to spruce bud- worm attack. In this study, we explored whether wood from dead (defoliated) or dying (partially defoliated) trees of these species could be treated successfully with ammoniacal copper arsenate or chromated copper ar- senate. We also studied the relationship of treatabil- ity to growth rate in three other softwood species (red pine, white pine, and eastern larch), which vary from slow grown (naturally grown) to fast grown (plantation grown). For all species, we studied the effect of incision on penetration and retention of preservative. Our re- sults demonstrate the positive influence of incising to improve preservative penetration of refractory species. Keywords: Waterborne preservatives, wood preserva- tion, ACA, CCA, treatability, northeastern softwood species, refractory species, eastern spruce, eastern hemlock, eastern white pine, eastern larch, red pine, incising, penetration, retention, spruce budworm February 1992 Gjovik, Lee R.; Schumann, David R. 1992. Treatability of native softwood species of the northeastern United States. Res. Pap. FPL-RP-508. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 20 p. A limited number of free copies of this publication are available to the public from the Forest Products Labo- ratory, One Gifford Pinchot Drive, Madison, WI 53705- 2398. Laboratory publications are sent to more than 1,000 libraries in the United States and elsewhere. The Forest Products Laboratory is maintained in cooperation with the University of Wisconsin. Treatability of Native Softwood Species of the Northeastern United States lee R. Gjovik, Research Specialist, Wood Preservation David R. Schumann, Technology Transfer Coordinator, State & Private Forestry Forest Products Laboratory, Madison, Wisconsin Introduction The treatability of three other softwood species (red pine, white pine, and eastern larch) was examined in The commercial value of several softwood species of relationship to growth rate (slow or fast grown). The the northeastern United States could be increased if question was whether relatively fast-grown wood ac- they could be treated to meet existing American Wood- cepts preservatives any differently than does naturally Preservers’ Association (AWPA) Standards (AWPA grown wood. 1986). These species include eastern spruce (red, white, and black [Picea rubens Sarg., P. glauca (Moench) Stake test plots have been established at the Harrison Voss, and P. mariana (Mill.) B.S.P.]), balsam fir (Abies Experimental Forest, Saucier, Mississippi, and in Cum- balsamea (L.) Mill.), eastern hemlock (Tsuga canaden- berland Center,. Maine. In addition, exposure decks sis (L.) Carr.), red pine (Pinus resinosa Ait.), eastern have been fabricated at the Harrison Experimental For- white pine (Pinus strobus L.), and eastern larch (Larix est and in Amherst, Massachusetts. Replicates of all laricina (Du Roi) K. Koch). Several of these species are test species and conditions, including untreated con- susceptible to spruce budworm attack; balsam fir and trols, are represented in the test plots and decks. Both eastern spruce are the most susceptible and are often the stakes and deck material have been monitored an- killed by the budworm. nually, and the results will be reported in the future. Smith (1986) studied the treatability of red pine, east- ern white pine, eastern hemlock, Norway spruce, (Picea Procedure abies [L.] Karst), European larch (Larix decidua Mill.), and bigtooth aspen (Populus grandidentata Michx.) Test Specimens and the effects of incising upon treatability. All speci- mens were treated with type-C chromated copper arse- All test material was collected in May 1984 from three nate (CCA) via full-cell impregnation. Incising caused sawmills in New England. Eastern spruce and bal- significant retention gains in eastern hemlock, Nor- sam fir were obtained from the Mountain View Lum- way spruce, and European larch. Sapwood penetra- ber Company (West Burke, VT) and P & R Lumber tion was good in each species; significant heartwood Company (Wolcott, VT). Eastern hemlock, eastern penetration was found in eastern white pine. Gjovik larch, red pine, and eastern white pine were obtained (1983) compared CCA and ammoniacal copper arsen- from the R. Leon Williams Lumber Company (East ate (ACA) treatment of Douglas-fir (Pseudotsuga men- Eddington, ME). All logs were marked on the ends ziessii [Mirb.] Franco) and Engelmann spruce (Picea with colored paint in the lumber yard or at the time engelmannii Parry ex Engelm.). of logging. Thus, the test material was tracked through the sawmill and into final dimension. The lumber was We studied the effect of incising on preservative pene- then shipped to Madison, Wisconsin. If possible, the tration and retention in several softwood species. We logs were quarter-sawn. This provided an adequate also studied whether wood from dead or dying trees supply of edge-grain samples and allowed us to select could be successfully treated with preservatives. Bal- heartwood. Edge-grain samples are desirable because sam fir, eastern spruce, and eastern hemlock at vary- they provide more consistent results by eliminating ing levels of budworm attack—from undefoliated to variation caused by cross grain. Heartwood was se- 100 percent defoliated-were examined for treatability. lected because the heartwood of most species is difficult The wood was visually examined to exclude decayed to treat. If the heartwood of a species can be treated, wood. the sapwood can most likely be treated as well. Table 1—Alphanumeric designation of test specimens Position of character Identification Code First Species F balsam fir A eastern hemlock L eastern larch R red pine S eastern spruce W eastern white pine a Figure 1—Incising pattern. Second Extent of budworm 1 undefoliated attack 2 approximately 50-percent defoliated Eastern spruce and balsam fir trees were selected 3 100-percent on the basis of budworm attack: (1) undefoliated defoliated (healthy), (2) approximately 50 percent defoliated, Growth rate 1 fast grown and (3) 100 percent defoliated (dead, but not de- 2 slow grown cayed). Eastern hemlock trees were selected on the basis of only two conditions: undefoliated and Third Log series 1 (butt log), 100 percent defoliated. The extent of defoliation 2, 3, . was determined by a subjective visual evaluation Fourth Sequence of pieces A, B, C,. of the crown of the standing tree. Red pine, white cut from log pine, and eastern larch were selected from natu- ral stands and plantations. Growth rate was deter- Fifth End-match as 1 unincised mined by comparing annual growth rings per inch related to 2 unincised (25.4 mm). incising 3 incised 4 incised When the material arrived at the Forest Products Lab- Sixth Location of final 1 1st piece from oratory, it was kiln dried to a moisture content of 10 to specimen log center 12 percent and then surfaced on four sides into nom- 2 2d piece . inal 2- by 4-in. (standard 38- by 89-mm) test speci- mens. Portions of each test specimen were incised with a 2 The treatability of balsam fir, eastern spruce, and 60 oyster-shaped incisions per square foot (0.09 m ). eastern hemlock was evaluated on the basis of The incising pattern is shown in Figure 1. extent of budworm attack. Bed pine, white pine, and eastern larch were evaluated on the basis Each specimen was marked with a 6-part alphanumeric of growth rate. designation, as described in Table 1. An example of marked test specimens is shown in Figure 2. eastern hemlock, and eastern larch) were treated using the higher pressure (150 lb/in2 (1,034 kPa)). Preservatives All wood specimens were precisely molded to 1.44 The preservatives selected for this study were ammoni- by 3.44 in. (36.58 by 87.38 mm) and precision end- acal copper arsenate (ACA) and chromated copper ar- trimmed to 18.00 in. (457 mm). This procedure al- senate (CCA). Water-borne salt preservatives were used lowed a single volume for each and every specimen. because refractory species are more difficult to treat Thus, the preservative retentions obtained during with water-borne preservatives than with oil-borne weighing of the specimens were very accurate. preservatives. This is particularly true of CCA. Each specimen was weighed before and after treatment All specimens were treated by the full-cell process, us- to determine the preservative or chemical oxide reten- ing the schedules shown in Table 2. The lower pressure tion in pounds per cubic foot (16 kg/m3). The treating (125 lb/in2 (861 kPa) was used for the treatment of solution concentrations were analyzed and calculated in eastern spruce and balsam fir to avoid cell-wall collapse. accordance with the AWPA Standards (1986) and held The other species (red pine, eastern white pine, constant at 2.5 percent oxide basis. 2 Table 2—Preservative treatments Solution Vacuum Time Pressure temperature Final Preservativea (inHg) (kPa) (min) (lb/in2) (kPa) (°F) (°C) vacuum ACA 28 95 30 125 861 135 57 None 150 1,034 CCA 28 95 30 125 861 Amb. Amb. None 150 1,034 a ACA is ammoniacal copper arsenate; CCA is chromated copper arsenate. purple-blue when copper is present and a salmon color when copper is absent. The preservative penetration patterns for all the test species are shown in the figures in Appendix A. The percentage of preservative penetration in each specimen was determined by subjective visual eval- uation of the cross-sectional area. The tables in Appendix A show values for individual specimens. These values can be compared to the penetration patterns illustrated in the figures.