Characteristics of wood

Answer 1

Characteristics of Wood

Sapwood:

Sapwood is the wood that conducts water and nutrients (sap) vertically in the tree. The higher the moisture content in the sap, the more likely checks (cracks) and splits will occur in the wood. Sapwood ranges in color from cream to light tan. It readily accepts stain and helps to create character in finished wood projects.

Heartwood:

Heartwood, the column that supports the tree, is sapwood that has lost its conductivity. It gives the tree its strength and often contains rich colors, depending upon the specie, because of chemical additives (extractives) in the cell walls. Heartwood is relatively dense and will shrink very little. It does not accept much stain, yet it contributes to beautiful contrasts in wood projects.

Growth Rings:

Growth rings are annual, and they consist of springwood and summerwood. The cell walls in springwood are thin and porous. The pores are large to aid in the movement of water. Springwood readily accepts stain. Summerwood (aged springwood) has thicker walls and smaller pores and helps to establish the grain pattern. It does not accept stain as readily as springwood.

Ray Cells:

Ray cells conduct horizontally and help to control shrinkage in hardwoods because they act as restraining rods that control expansion from the center. 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 because they (if present) are planes of weakness that contribute to v-shaped splits (checking), honeycombing, and fissures. When cut, the end fibers may split and cause the wood to absorb excessive stain. This can result in very dark places in the finish of a wood project. Ray cells are very fine in softwoods and, therefore, do not present conspicuous problems.

End Grain:

All wood used in projects will have some end grain. As with ray cells, fibers in end grain may split and absorb excessive stain.

Grain Defects:

Defects in wood grain can be caused by environmental factors that can lead to twisted grain (spiral); interlocking grain such as that found in sycamore; knots that can star-check or crack; compression wood (in conifers) which pushes a branch against the pull of gravity; and tension wood (in hardwoods) which pulls a branch up.

Spalted Wood:

Spalted wood is caused by fungus, a living organism, that obtains its nutrients from living wood cells. Unchecked, fungus will destroy the wood. It also poses health risks to wood workers who do not take the proper precautions.

Answer 2

Spring wood has darker annual rings than summer wood.

Answer 3

the xylem cells formed in summer and spring i-e period of fast growth forms the summer wood and these are thin walled and bigger in size....