A plan usually names a wood, and plans are often written for whatever the designer had in the shop. Choosing a different species is reasonable, and it is much easier once you know what the differences are. Five properties account for most of them: hardness, grain pattern, movement, workability and cost.
Softwood and hardwood
The words describe the tree, not the feel. Softwoods come from conifers such as pine, fir, cedar and spruce. Hardwoods come from broadleaf trees such as oak, maple, cherry and walnut. Most softwoods are lighter and dent more easily, and most hardwoods are denser, though there are exceptions: basswood and poplar are hardwoods that are soft and easy to cut, and some pines are hard.
Hardness
The Janka hardness scale measures the force in pounds to push a steel ball halfway into a board. The woods database gives the figure for each species. Some reference points:
| Species | Janka (lbf) | Character |
|---|---|---|
| Eastern white pine | about 380 | Very soft, dents easily |
| Western red cedar | about 350 | Soft, light, aromatic |
| Yellow poplar | about 540 | Soft hardwood, paints well |
| Black cherry | about 950 | Medium, darkens with age |
| Black walnut | about 1,010 | Medium, rich brown |
| White oak | about 1,350 | Hard, pronounced grain |
| Hard maple | about 1,450 | Hard, pale, fine grain |
Hardness decides how a surface handles daily use. A tabletop in pine shows dents from a dropped spoon. A maple or oak top takes the same treatment with far less mark. Shelves that hold books do not need a hard wood, but a workbench top does.
Grain and appearance
Open-grained woods, such as oak and ash, have visible pores and a strong figure. They take stain unevenly in places but give a pronounced pattern. Closed-grain woods, such as maple, cherry and birch, are smoother and more uniform. Cherry darkens from pale pink to deep red-brown over a year or two in light. Walnut is chocolate brown, and sometimes lightens. Poplar is pale with green or grey streaks, and is usually painted.
Movement
Wood swells and shrinks across its width as humidity changes. Species differ in how much. The woods database lists a movement rating of low, moderate or high. Quarter-sawn boards, cut with the growth rings near perpendicular to the face, move less than flat-sawn ones. For a wide panel, a tabletop or a door, a low-movement species and a design that allows the wood to expand keep it flat.
Workability
Workability is how the wood responds to cutting, planing, sanding and screwing. Easy woods such as pine and poplar cut cleanly and take screws without splitting. Some hardwoods, especially maple and cherry, burn when cut slowly and need a keen tool. Woods such as oak have open pores that tear when planed against the grain. Interlocked-grain woods, such as sapele, can tear out if planed in one direction. The database notes the quirks of each species.
Colour
Colour matters in matching a piece to its room, and it also changes. Pale woods, such as maple, birch and ash, stay light and yellow slightly. Walnut can lighten in sun. Cherry darkens. Exotic woods, such as padauk, start as a vivid red-orange and turn to brown. If a finished piece is to be stained, choose a wood that accepts stain evenly: oak, ash and walnut are good; pine, maple, birch and cherry can blotch without a conditioner.
Price and supply
Prices are given in the database as low, medium or high. Construction lumber such as pine, fir and spruce is at the lowest end, sold as dimensional lumber in standard sizes. Hardwoods are sold by the board foot, which is a volume of 144 cubic inches: 12 x 12 x 1 inch. The board feet calculator gives board feet and cost for boards of a given thickness, width and length. Expect rough lumber to cost less, but it requires milling to a flat, square board, and a lot of the weight is lost.
Matching species to projects
| Project | Good choices | Why |
|---|---|---|
| Painted shelves, cabinets | Poplar, pine | Stable, cheap, takes paint |
| Bookcase, stained | Oak, ash, birch plywood | Takes stain, strong |
| Dining table | Maple, oak, walnut, cherry | Hard, resists dents |
| Outdoor furniture | Western red cedar, white oak, teak, redwood | Durable in weather |
| Boxes and small pieces | Cherry, walnut, maple, basswood | Fine grain and looks |
| Workbench | Maple, beech, southern yellow pine | Hard or cheap and thick |
| Carving | Basswood, butternut | Soft and even |
Substituting
To replace a species in a plan, match hardness and movement first, then colour and price. The wood substitute tool takes the wood a plan calls for and the type of piece, and gives alternatives from the database. If you have a board and want to know what it is, the species tool takes a photo and makes a guess, with notes on how it works and takes a finish.
Buying boards
Look along the edge of each board to check that it is flat, not bowed or cupped. Look at the ends for checks, or cracks. Choose boards from the same batch so that the colour matches, and buy an extra 15 to 20 percent for offcuts and for defects that have to be cut out. Stack them flat in the workshop for a few days before cutting, so that they reach the moisture of the room and do not move after you have cut them.