Two ammoniacal preservatives, copper-arsenic-additive (CCA) and copper-zinc-arsenic-additive (CZAA) - developed at the Eastern Forest Products Laboratory for difficult-to-penetrate wood species - were tested in a commercial treating plant on Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) plywood. The inner plies were spruce (Picea sp.) fir (Abies sp.), and hemlock (Tsuga sp.) - all can be difficult to penetrate with aqueous solutions. The treatment schedule comprised steaming for 1.5 or 2.75 h followed by a standard full-cell treatment for 1.5 or 4h (the longer schedule was used with CZAA). There was little strength loss due to treatment and no evidence of wood collapse. Cores taken from the center of the plywood faces showed: (1) the preservative had penetrated all 5 plies; (2) plywood treated with a 3.2 percent oxides solution of CAA retained 9.3 kg/m3 (0.58 pounds per cubic foot) oxides; and (3) plywood treated with a 2.2 percent oxides solution of CZAA retained 9.9 kg/m3 (0.62 pounds per cubic foot) oxides.
Preserved wood foundations (PWF) are gaining increased acceptance by builders and home owners in certain areas of Canada. The use of masonry veneer as an exterior cladding, alone or in combination with wood, hardboard or aluminum siding is in common use in many municipalities across the country. The technique of supporting masonry veneer on wood foundation is completely new, however, and a performance history based on traditional practise has not been developed. Consequently, building codes have not defined minimum standards of construction for this building system. This field study was initiated and partially supported by the Canadian Wood Council through its Wood Foundation Committee to identify wood foundation houses that utilize masonry veneer cladding and to observe how the cladding was performing in service. Information was obtained on the construction details of the supporting walls and other specialized features of the structure. Notes were taken, wherever possible, on the type of drainage employed.
This report is to present data obtained in an examination carried out on apile of incised and non-incised spruce poles in Delson, Quebec, on August 14, 1979. The examination was part of a study titled "Investigations of the Treating Characteristics and Performance under Subsequent Service of White Spruce Poles Preserved under Plant Conditions". The working plan (EFP-23-191) was prepared by J. Krzyzewski and J.K. Shields in 1977.
Treatment of spruce species with preservatives for poles and their field performance : investigations of the treating characteristics and performance under subsequent service of eastern spruce preserved under plant conditions
Black liquiors from kraft pulping and as well as a purified kraft lignin were reacted with formaldehyde over the temperature range 30-70C. The activation energy was about 12.9 Kcal per mole. They were also heat treated to "activate" the lignin and some were also reacted with formaldehyde or furfuraldehyde. These treated solutions were then mixed with phenolformaldehyde (PF) resols and used as plywood adhesives. They were first used in suspension at pH 5.3-5.5 with an acid-curing PF resin. This method proved unsatisfactory. When used as solutions mixed with polymethylophenol resols at solids content varying from 40 to 60 per cent of total solids (resol solids plus black liquor solids) and pH about 12.0, good bonding was obtained with either crude or methylolated black liquor or kraft lignin solutions on 3/8 inch (9.6mm) aspen poplar plywood pressed at 350F (177C) fro 5 minutes and 150 per square inch (1034 kPa). Phenolic resin requirements were 40 to 56.5 percent of the amount required when pure PF is used.
Waferboards were made from 5 and 9 year old hybrid poplars, using laboratory prepared wafers. The binder was a powder consisting of a mixture of phenol-formaldehyde (PF) resin and comminuted hybrid poplar bark in equal weights. Only 1.25% PF resin was used based on weight of dry wood. These boards had bending strength and internal bond strength much in excess of the minimum required by Canadian Standards. Another binder was used composed of white spruce tannin, hybrid poplar bark and PF. This amount of PF based on dry wood was 0.5%. this mixture also gave strong boards, both dry and wet, at densities of 42 pounds per cubic foot.