The Beauty of Turned Art lies first in the Characteristics of Wood
Characteristics of Wood:
Trees do not grow on this old ball we call Earth to satisfy a wood turner's desire to create art. So, to help you understand the nature of wood, and to enhance your appreciation for art turned from wood, some of the basic characteristics of wood are discussed below.
Sapwood: This is the wood that conducts sap (water and nutrients) vertically in the tree. The higher the moisture content, the more likely checks and splits will occur. It ranges in color from cream to light tan. Sapwood will shrink more than heartwood, and it readily accepts stain, so it helps to create character in the finished wood turned product.
Heartwood: When sapwood loses its conductivity, it turns into heartwood. Heartwood gives the tree its strength and often contains rich colors, depending upon the wood specie, because of chemical additives in the cell walls called extractives. Heartwood (the column that supports the tree) is relatively dense, so it will not shrink much. Because of its density, it will not accept much stain. The characteristics of heartwood contribute to beautiful contrasts in a finished bowl.
Growth Rings: The annual growth rings consist of springwood and summerwood. The cell walls in springwood are thin and the pores are large which aids in the movement of water. Springwood readily accepts stain. Summerwood helps to establish the grain pattern and has thicker walls and smaller pores. Summerwood does not accept stain as readily as springwood.
Ray Cells: Ray cells conduct horizontally. They radiate outward from the center of the tree and form into stacks of flattened tissue bands. Tissue bands in hardwoods, though small in number, can pose real problems for wood turners because they (if present) are planes of weakness that contribute to v-shaped splits (checking), honeycombing, and fissures. While being turned on a lathe, the end fibers of ray cells may split. If they do, the wood may absorb excessive stain causing very dark places in the finish. The ends may not seal well when the bowl is finished, and may cause some dry areas, over time. Ray cells help to control shrinkage in hardwoods because they act as "restraining rods" that control expansion from the center. Ray cells are very fine in softwoods, so they do not present conspicuous problems.
End Grain: All bowls have end grain. At times, the characteristics of wood in the end grain can create problems similar to those caused by ray cells.
Grain Defects: Some of the defects in the characteristics of wood that can affect wood turning include a twisted (spiral) grain usually caused by environmental factors; an interlocking grain such as that found in sycamore; knots that can star-check or crack; compression wood (found in conifers) which pushes a branch against the pull of gravity; and tension wood in hardwoods which pulls a branch up.
Fungus: Fungus, a living organism, obtains its nutrients from the living wood cells. Unchecked, fungus will destroy the wood. It also poses health risks to wood turners who do not take the proper precautions. If you are new to wood turning, take the time to learn about the hazards associated with working with spalted wood.
Wood Toxicity: Separate from focusing entirely on the dangers presented by working with spalted wood, wood toxicity is another health risk that bears serious consideration. Click here on
to learn more about this subject.
Kiln Dried: I turn all of my work from kiln dried wood. In a kiln, the wood is heated to above 130 degrees. This kills all insects, larvae, eggs, and fungi. It also prepares wood to "live" indoors by removing most of the moisture. However, even kiln dried wood will shrink and expand - wood is never completely still.
These are some of the characteristics of wood that contribute to the beautiful contrasts in turned wooden bowls, as well as to those things some may see as imperfections. At times, turned bowls require extra care because of the nature of wood. And so - that is just how it is.
About the Finish and Its Care
Every wood turning of mine is finished with four coats of polyurethane. The first coat is a gloss coat. The next three coats are satin. Because of the shape of the piece, small runs of polyurethane may occur in the finish. That is the nature of this type of hand finishing and not a flaw of workmanship.
Your Classic Woodturned Keepsake needs to be oiled (Antique Oil by Minwax is good) or waxed, periodically, to keep its luster. Johnson's Paste Wax is an excellent choice. The best place to find Johnson's Paste Wax is your local Ace Hardware Store.
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