Western yellow pine

Pinus ponderosa (Western yellow pine, pondoosa pine)... 

Schoi er has examined the oil distilled from the leaves and twigs, and also that from the cones of Pinus ponderosa, the Western yellow pine, and found them to have the following characters —... 

Figure 1 Changes in color of outdoor weathered western red cedar, redwood, southern yellow pine, and Douglas fir in the USA. (From Ref. 16.)...

Figure 6. Decrease in brightness of outdoor weathered wood. Key , western redcedar , redwood , southern yellow pine and O, Douglas-...

Figure 23. Comparison of ESR relative signal intensities (carried out in a vacuum) of free radicals in early wood with different moisture contents. Key SYP, southern yellow pine WHC, western redcedar DF, Douglas-fir and flW, redwood.

Discussing sap-stain on soft woods, Boyce says, Certain species are peculiarly susceptible to sap-stain. This is due both to toe character of toe wood and to the climatic conditions of the region where toe species growB. Western white pine, Bpruce, raid southern yellow pine, toe last-named wood including longleaf pine (Pinus palustris Mill.), shortleaf pine (P. echinata Mill.), and loblolly pine (P. tmda Linn.), are very subject to sap-stain, especially blue-stain, while true fir and cedar are not so easily affected. Douglas fir occupies an intermediate position. 

Two mechanisms have been identified. Most of the so-called chemical stains result from oxidation of certain wood extractives by air during air seasoning or kiln drying. Colors observed include shades of brown, blue, green, yellow, and red. Species include both hardwoods (oak, birch, maple, alder, basswood, gum, etc.) and softwoods (eastern and western pines, hemlock). 

Parallel strand lumber is manufactured from veneer about 3 mm (1/8 in.) thick, that is clipped into strands about 19 mm (3/4 in.) wide and 0.6 m (24 in.) long. The produet was designed to use waste material from the roundup lathe as well as other less than full-width veneer arising from plywood manufacture (Chapter 11). Species eommonly used for PSL include Douglas fir, southern pines, western hemlock and yellow poplar, but there is no restriction on the use of other species. 

Relatively weak absorptions at wavelengths above 400 mn are snfficient to cause the perception of color. The color of woody tissue varies widely from off-white (e.g., aspen, birch), yellow (e.g., spruce, pine, fir), amber-orange (e.g., western hemlock, Douglas fir, red cedar, teak) and rich browns (walnnt). While some of this color is dne to tannins and other extractives, in most species the color originates from chromophores in the lignin. 

Joints bonded with casein glue will average better than 90% wood failure when the following softer wood species are used redwood, western red cedar, white fir, Sitka spruce, southern cypress, western hemlock, eastern red cedar, chestnut, red alder, and northern white pine. With the harder woods—red oak, maple, white ash, yellow birch, and persimmon—the joints will show 30-50% wood failure. 

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