Color and Grain Characteristics
Color and grain patterns are the primary factors influencing the appearance of wood. Other characteristics such as stains, burls, and insect damage also have an effect. All are variable, not only in different commercial groups of wood, but within a given species, log, or board. (This infinite natural variety is one of wood's greatest selling points). Each window or door contains wood color variation that may be either enhanced or hidden when the finish color is applied.

Color Variation Influences

The natural causes of color variation within a species are influenced by many factors. Soil types, minerals, water levels, available sunlight, temperature, and genetic composition, all contribute to color variation.

Hardwood trees regenerate from seeds, root sprouts, and stump sprouts. Trees originating from seeds contain genetic variables from two parent trees, while sprouts from roots and stumps will be genetically identical to the parent tree. Because of these variables, trees of the same species from one area may be quite different from that of other areas.

The actual color variations are caused by natural chemical extractives found in the cell walls of wood. The hues produced through these deposits cover a wide range and are traceable to four spectral colors: red, orange, yellow, and violet. Other natural influences such as fungi may also contribute to some color variations.

The range of color variation in a commercial lumber group may be increased by the mixing of species, such as northern red oak and pin oak within the red oak commercial group. Logs of these species are normally not separated by sawmills. This mixed lumber will increase the color variation in products manufactured from this material.

Grain Variation Influences

Grain variation, like color variation, is influenced by many factors. They include, but are not limited to, tree size, growth rate, climate changes, site conditions, genetics, bird, insect, and fire damage.

Plain Sawing (Flatsawn)

Plain sawing is the most common method of sawing and consequently most lumber is plain sawn, unless specified otherwise. Plain sawn lumber is obtained by making the first saw cut on a tangent to the circumference of the log and the remaining cuts parallel to the first. This method provides the widest boards and least waste; therefore, it is the most economical. About half of the lumber produced by plain sawing is of tangential grain and the other half is of radial grain.

Tangential grain is usually called flat grain and is easily recognized by its cathedral (Gothic arch) effect. Lumber is considered flat grained when the annual growth rings make an angle of less than 45 degrees with the surface of the board.

Radial grain is known as vertical grain or edge grain, and is generally more dimensionally stable than flat grain. Lumber is considered vertical grain when the annual growth rings make an angle of 45 to 90 degrees with the wide surface of the board.

Quarter Sawn

Quarter sawn lumber is produced by first quartering the log and then sawing it perpendicular to the growth rings. All of the boards sawn thus are of radial grain. This method of sawing produces relatively narrow boards and creates more waste. For these reasons (and the additional handling involved) quarter sawn lumber is much more expensive than plain sawn.

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