textures to create photo-realistic renderings.
~ Bruce Kieffer
Introduction to Wood
Choosing lumber for your project is as much a part of woodworking as any other step in the process. Lumber is expensive, so it pays to know what your options are before you head to the lumberyard—sometimes an economical species will serve the same function as a more costly alternative.
In addition, each wood type has natural characteristics that influence workability, appearance and durability. It’s important to be aware of these factors before you build. Hardwood and softwood lumber is sold in various industry grades based on the percentage of clear (knot-free) lumber the board must have, as well as whether or not the boards are planed at the mill or left roughsawn. You’ll need to pick a lumber grade that is suitable for your project needs, tools available to you and your project budget, then sift through stacks of boards carefully—lumber within the same grade can vary widely in terms of color, figure and defects.
WOODWORKING WORKS
One of the distinctive features of this tool chest is how the design integrates contrasting wood types. While the majority of the project is made of white oak, the drawer pulls and lid edge are walnut. Generally, the most attractive approach is to pair light and dark woods and limit the contrast to two wood types.
So how do you choose which species to use and which boards to buy? Making good lumber choices to some extent comes only by experience. You’ll need to build with different species and grades of wood to know what truly works best for projects intended for different purposes. But familiarizing yourself with the various topics covered in this chapter is a good first step to buying smart.
In the pages that follow you’ll become familiar with distinctions between hardwoods, softwoods and sheet goods and examine some of their different uses. Learn about figure and defects in lumber, see how mills cut logs into boards, and discover how wood reacts to changes in moisture. We’ll cover how lumber is sized and sold, as well as overview the standardized lumber grading systems. Finally, the end of the chapter reveals some time-tested guidelines about where and how to shop for lumber like a pro.
Once you’ve read this chapter and calculated the quantity and quality of boards your project requires, you can venture more confidently off to the lumberyard to pilfer through stacks of boards. You may even save a bit of money in the process.
Woodworking Wisdom
A woodworker in Wyoming once sent me some photographs of a cigar humidor he had built from a plan of mine. It was a Honduras mahogany box with brass inlay, a gift for his father-in-law who enjoyed an occasional stogie. The accompanying cover letter said that he was especially proud of the beautiful cedar lining that he had custom-fitted to the interior. But when I got to that photo, my heart sank. This well-intentioned fellow had unfortunately lined the humidor with aromatic instead of Spanish cedar. If the humidor had been used, his father-in-law’s cigar collection would have been ruined by the strong cedar smell. Instances like this illustrate an important lesson when selecting wood for a project: Be sure to consider the characteristics of the wood species you choose before you build. It can make or break a project.
~John English
Anatomy of a Tree
At the very center of a tree is a small area of softer tissue called pith. Surrounding the pith are numerous annual rings of growth, already dead, that provide support and structure to the tree. This is the heartwood, the area most treasured by woodworkers because of its even density and grain pattern. Beyond the heartwood is a thinner section of still-living rings, called sapwood, that provide a conduit from the roots to the leaves for transporting soluble mineral salts. The outermost sapwood ring—the cambium—is the growth region in a living tree. Cambium contributes girth to the trunk over time, adding another new layer of sapwood each year. Between the cambium and the protective layer of bark is yet another thin region called the phloem. This is the conduit that brings food (made in the leaves through photosynthesis) back down to the root system.
Most mills remove all the exterior layers (bark, phloem, cambium and sapwood) from logs before milling them into boards or dimensional stock such as 2 x 4s. Today, most of the bark and sapwood is ground up and used as mulch in gardens, sold to paper mills, burned as fuel or even used as animal bedding. Occasionally you’ll run across a board at the lumberyard that contains sapwood. In darker-grained varieties, like walnut or cherry, sapwood appears as a band of lightly colored, softer wood that runs lengthwise near one long edge of the board. If incorporated into a project, sapwood will become more prominent when you apply a finish unless you stain it to match the rest of the board. For this reason, sapwood is seldom used for furniture.
This Chinese Elm sample exhibits all the major anatomical areas of a tree: bark, phloem, cambium, sapwood, heartwood and pith. The cross-section shown here, with two pith regions, likely came from a tree whose trunk split into two major branches. Notice also the darker area, a sign that the tree experienced a period of injury or disease.
FOREST MANAGEMENT
Softwoods (also called conifers) nearly always grow at a faster rate than hardwoods, and this fact helps explain how supply and demand influence prices of both softwood and hardwood lumber. The rapid growth rate of softwoods allows for frequent replanting and harvesting—sometimes in as little as 15 years—compared to a minimum of 75 years for most common hardwoods. Shorter harvest time helps to keep softwood quantities stable and costs below that of hardwoods—a benefit to both the construction industry and to softwood supplies for woodworking.
Because softwood trees reproduce with heavy cones rather than flowers or nuts, the seeds often fall close to the parent tree. This natural adaptation enables softwoods to grow close together—a fact that can be a boon to a lumber mill. The mill’s forester can plant more trees per acre. Each plant, seeking light above the canopy created by its siblings, will tend to grow straight and true. Loggers have long taken advantage of this growth pattern, replanting conifers in tightly spaced rows that yield easily milled, straight logs.
Softwood seedlings (right photo) are planted in tightly-spaced rows, then transplated in wider rows (top photo) until they mature into trees suitable for lumber harvest. Note the tall, straight trunks—a characteristic trait of softwood trees.
Defining Hardwoods & Softwoods
Botanically speaking, trees are categorized as either hardwoods or softwoods. Here’s a simple way to distinguish the two: hardwoods are deciduous (broad leafed), generally losing their leaves in late fall and reproducing with flowers and fruits or nuts. Softwoods, on the other hand, are coniferous; they retain their needle-shaped leaves in the winter and reproduce by spreading their seed through open cones. The terms ‘softwood’ or ‘hardwood’ have nothing to do with whether the wood is physically hard or soft.
All trees have two growth spurts each year. Their spring growth produces a light-colored material between the rings, called earlywood. The more dense cells produced in the late summer and fall are known as latewood, and these constitute the darker rings that every child has counted to determine a tree’s age.
Softwood trees tend to grow more rapidly than hardwoods, and they have wider bands of earlywood than