Douglas-fir

Northwest Douglas fir and hemlock tme firs and spmce red alder ... 

Fig. 4. (a) Photomicrograph of Douglas fir kraft pulp (b) electron micrograph of Douglas fir pulp collapsed into paper. 

Sulfite pulps have properties that are desirable for tissues and top quaHty, fine papers. Because sulfite pulping is not as versatile as kraft pulping, various options have been developed, and the choice of a specific process is dependent on individual mill situations. The unbleached pulp has high (60+) brightness compared to kraft pulp and is easily bleached. However, it is limited to select wood species. The heartwood of pine, Douglas fir, and cedars are not easily pulped. Additionally, pulps produced from hardwood have limited economic value because of low strength. 

Fig. 6. Permanent effect of heating in water (—) and in steam (-) on the modulus of mpture. Data based on tests of clear Douglas-fir and Sitka spmce.

Eor practical purposes, the sapwood of all species may be considered to be susceptible to biodeterioration. The heartwood of some species, however, contains toxic extractives that protect it against biological attack. Among the native species that have decay-resistant or highly decay-resistant heartwood are bald cypress, redwood, cedars, white oak, black locust, and black walnut (60). Douglas-fir, several of the pines, the larches, and honey locust... 

The moisture content of freshly cut wood varies between species and portions of the tree. Between species, it can be 30—70% on a total weight basis (65) commonly, it is 45—50%. Within a tree, the heartwood generally has lower moisture content than the sapwood. For hardwood species, this difference is usually small for softwood species such as Douglas-fir, the difference can be as great as 30% for heartwood compared with 50% for sapwood. 

Wood and Wood-Lined Steel Pipe Douglas fir, white pine, redwood, and cypress are the most common woods used for wood pipe. Wood-lined steel pipe is suitable for temperatures up to 82°C (180°F) and for pressures from 1.4 MPa (200 Ibhin ) for the 4-in size, through 0.86 MPa (125 IbFin ) for the 10-in size, to 0.7 MPA (100 Ibf/ in") for sizes larger than 10 in. For fume stacks and similar uses, wood-stave pipe with rods on 0.3-m (1-ft) centers is most satisfactory because it permits periodic tightening. In recent years reinforced plastics have supplanted wood pipe in most applications. 

This makes a mix with a viscosity of 5000-7000 centipoise. The total mix solids are 40% and the resin solids in the mix are 26%. A mix like this would be used on Douglas fir veneer at the rate of about 55 pounds per 1000 square feet of veneer surface (double glue line basis). The 43% solids resin would be used at about 500 cps viscosity. 

Metals in contact with or in the proximity of timber can suffer enhanced corrosion attack. Some species of timber, especially oak and Douglas fir, contain high levels of acetic acid. These are volatile and cause corrosion of nearby metals, especially iron, steel and lead alloys. 

Impermeable timbers have a good resistance to polluted atmospheres where acid fumes rapidly attack steel. Wood has given excellent service in the buildings of chemical works and railway stations. Permeable wood species and sapwood can suffer defibration problems caused by the sulphur dioxide of industrial atmospheres. Tile battens are particularly vulnerable. The heartwood of Douglas fir, pitch pine, larch, Scots pine/European redwood and many tropical hardwoods give good service in these conditions. 

Pink stains occur naturally in some acidic woods, e.g. oak and Douglas fir, but similar anthocyanidin stains can be produced in the wood of sycamore, maple, walnut, agba and sapele by acid-catalysed adhesives. A variety of enzymatic stains can be produced at mildly elevated temperatures in the... 

Edmonds, R. L. (1979). Decomposition and nutrient release in Douglas-fir needle litter in relation to stand development. Can. f. For. Res. 9,132-140. 

The third paper in this set Zavarin and Snajberk (1976) described their efforts to detect chemical races within big cone Douglas fir. Analysis of the cortical monoterpenoid fraction of 33 trees revealed that the major component was a-pinene, with P-pinene, 3-carene, and limonene present in lesser amounts. The monoterpene profiles of different populations varied somewhat from each other, but the overall profile of big cone Douglas fir was clearly different from that of Douglas fir. There was no evidence for gene flow between the southernmost population of Douglas fir at Lompoc and the closest population of big cone Douglas fir at Figueroa, sites separated by only 34 km. 

Foliage of Douglas fir had only trace amounts of (+)-camphene in trees from the coast but major concentrations in trees from the other three sites, hi contrast, ter-pene mixtures from lodgepole pine leaf and bole tissues had nearly the same levels of the major compound, (-)-P-phellandrene, and minor components regardless of origin. Patterns of variation in the other species were less extreme. 

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