Understanding Wood
Wood comes in two flavors, hardwood and softwood. Hardwood comes from deciduous trees, broadleaf trees such as oak, walnut and maple. Softwood comes from coniferous trees, cedar, pine and fir - cone bearing trees sometimes called evergreens. Hardwood and softwood are confusing terms not to be taken literally. The wood from some softwood trees is harder than wood from some hardwood trees. Yew, a “softwood,” is much harder than balsa, a “hardwood.” Stay with the program, “hardwood” deciduous trees; “softwood,” conifers. Most furniture is made of hardwood, oak, cherry, walnut. Houses are built of softwood, two by four pine and fir.
Looking at a board of hardwood, say, oak, you see two things. Its color and the pattern on the surface which we call the grain. The color is typical of its species, oak is a khaki brown, but the tone of the color varies enormously from tree to tree, as does the color in every species.
The grain and gradual change in the pattern of the grain is a consequence of where the board was cut from in the log. The diagram shows the outside, or first cut boards to the boards at the center of the log. The looping character of the grain on the first board is called a “cathedral figure” because it mimics, to some degree, the arches used in the construction of cathedrals. The grain on the board cut from the center of the tree is referred to as a “straight grain” board. The board between these two has some of each grain type with cathedral figure up the center and straight grain on each edge. The straight grain on this board is called “rift sawn.” Although the grain is straight, it differs significantly from the straight grain of the quarter sawn board. The difference is apparent if you look at the direction of the growth rings on the end of each board. The growth rings on the quarter sawn board are vertical to the surface of the board. The growth rings on the rift sawn board are at an angle of 45 degrees or higher.
But there is another factor at play. On the end of the log, you will notice lines going out radially from the center of the log. The lines are not continuous like the spokes of a bicycle wheel, they are sporadic, some long, some short. These are plates of tissue where the tree stores food called “rays.” Every tree has them. You could imagine them to be flat discs, saucer like. What you see on the end grain is the saucer sawn across at some point – some at the edge, some at the middle of the saucer so they are different lengths. On the quarter sawn board the rays are parallel to the surface of the board so what you see is the surface of the saucer showing the ray at its most visible. On the rift sawn board, you are seeing the edge of the disc or saucer. It is visible but in no way prominent.
Oak has particularly large and thick rays. On a quarter sawn board they are very prominent.
A piece of furniture made using quarter sawn oak, selecting the parts so that there is a visual unity between the pieces is a sign of care and skill that you should find throughout the piece.
“Selecting the stock” is the first task in getting the parts together to make any piece of furniture. Two things are vital, color and grain. You might imagine that all oak is the same color but it's not. Getting all of the parts to match color wise will take time searching through many boards of wood. An alternative is to take pieces as they come, then, at the end of the making, stain all the parts the same tone or color. Wood stain is a material not found in my workshop or on my work.
As to the grain, it should be aligned with the shape of the part. That is to say, it should be parallel to the edges of the part. Boards from which the part is to be cut sometimes come with the grain aligned with the edge of the boards, mostly not. Then, the part is cut from the board at an angle to achieve grain alignment. On this furniture you will find that the grain pays a lot of attention to the part.
