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About Wood

Click on these suggestions for caring for your wood pieces and some technical information on wood species.


Caring for Wood

Light and moisture affect wood. ALL wood darkens with age because the chemicals in the wood react with light. Some have said that eventually," All wood turns black!" We should live that long. Direct sunlight should be avoided.

Use only a damp cloth to clean pieces that are intended as salad bowls, cheese plates or serving platters. Then dry thoroughly. Those pieces will have been finished with walnut oil that polymerizes upon drying, making the wood somewhat more water resistant. Occasionally, refresh the surface with walnut oil or mineral oil. Decorative pieces may have a similar oil finish, lacquer, polyurethane, or may simply be buffed, with a final Carnauba wax finish.Treat these pieces as you would your fine furniture. Clean with a soft cloth. NEVER use furniture polish or oil.
 

Should the surface of a piece ever be scratched or marred, very fine grit wet sandpaper (400 to 1200) can be used in sequence to restore the surface. Such repair can often remove surface patina or color, resulting in spot more noticeable than the damage. In an extreme case of damage, I can refinish a piece to near-original surface quality, but any patina or color darkening will be lost upon refinishing.


Spalted Wood

Notes from J.Boyce in Forest Pathology, (1948): "Narrow zone lines, usually black but sometimes dark brown, are a common phenomenon of many decays. They are frequently formed in the white rots, and they are more common in decayed woods of hardwoods than in conifers. At times black zone lines may be fantastic in pattern." Boyce goes on to identify the various fungi, bacteria and parasites responsible for each type of decay and the characteristics and colors typical of each.

In essence, a fungus first invades the wood (incipient decay), establishes itself, and then breaks it down. The zone lines mark the intermittent progress of each type of fungus as it advances into the wood, or the point where the tiny filaments (mycelia) of two competing fungi clash for possession of the tree's tissues. Generally the wood is softer behind each zone line and harder ahead of it. Says Boyce, by way of example, "In aspen, three stages of decay have been recognized. In the incipient stage the wood is faintly colored from light pink to straw-brown; in the intermediate stage it is colored from straw to chocolate-brown, but it is still hard and firm; and in the advanced stage is included all soft, punky wood irrespective of color. Wood in the incipient and intermediate stages is utilized for some purposes but in the advanced stage is always rejected."

Spalted Bowl

RELATIVE HARDNESS and SHRINKAGE

The Janka (or side) hardness test measures the force required to embed a 0.444 inch steel ball to half its diameter in wood. This is one of the best measures of the ability of wood species to withstand denting and wear. It is also a good indicator of how hard a species is to saw or nail.

The tangential to radial shrinkage ratio suggests how much distortion may occur upon drying a specimen of the wood. While all my work is dry when completed, wood does change moisture content as the relative humidity of its surroundings change. Those species with high shrinkage ratios may take on an oval shape, or the rims of bowls may curve upward near the pith, over time. Among the wood I use frequently, madrone is particularly prone to these affects. Madrone also contains more water while green, contributing to distortion upon drying, a property frequently exploited by wood artists of the Northwest.

In extreme cases, the drying stresses, or stress caused by asymmetrical growth, will cause wood to split. If you move from the coastal Northwest to say, the desert Southwest, be prepared for the possibility of some splits opening.

     Species      Janka Hardness Shrinkage Ratio Species Janka Hardness Shrinkage Ratio
Red Alder 590 1.65
Douglas Fir 660 1.56 Hard maple 1450 2.05
Bigleaf Maple 850 1.91 Pacific Yew 1600 1.35
Pacific Madrone 2.21 Wenge 1630
Black Cherry 950 1.92 Black Locust 1700 1.56
Teak 1000 2.75 African Padauk 1725
Black Walnut 1010 1.41 Hickory/Pecan 1820 1.82
Yellow Birch 1260 1.52 Purpleheart 1860
Red Oak(Northern) 1290 2.15 Jarrah 1910
American Beech 1300 2.16 Merbau 1925
Ash 1320 1.59 Santos Mahogany 2200
White Oak 1360 1.88 Mesquite 2345
Australian Cypress 1375 Brazilian Cherry 2350