For plain work avoid "cross-grained" stock, as well as that having knots (which are sometimes "tight" and sometimes "loose"), as it is harder to work and to smooth, is not as strong, and does not hold its shape as well, as a rule. Sometimes it is desirable, however, on account of the beautiful figure of the grain shown in many crooked-grained pieces, as in mahogany for furniture (see [Appendix]). Bear in mind that when especial strength is required rift stock is best.
Reject wood which smells musty, or has rusty-looking spots, which are signs of decay, or of the attack of fungi, which may spread and under favourable conditions attack other pieces which are sound (see [Appendix]).
Fig. 29.
Fig. 30.
Reject crooked stock. The worst form is winding or twisting. Of course no one would take such an extreme case as Fig. 29, unless for some very rough work, but even a very slight winding may make much trouble in your nice work. So look particularly for this defect, which you can often detect at once by the eye, but if your eye is not well trained use winding-sticks (see [Part V].). Warped or curled stock, with the surface rounded or hollowed (Fig. 19), is also bad, but you will need no instructions to detect this defect by the eye or any straight stick. When boards are rounding on one side and hollowing on the other, it is due either to the way the log was sawed, as we have seen, or to one side having been more exposed and so having dried faster and shrunk faster than the other, causing that side to be concave, while the other became convex. Stock is sometimes crooked lengthways,—either a simple bending in a curve or at an angle, or wavy (Fig. 30), or both,—often due to careless "sticking" (Fig. 28) while the wood was green. Sighting lengthways will of course show these defects.
Reject stock badly checked at the ends, or cracked. There is apt to be more or less of this in most lumber. In seasoning, the pieces dry faster on the outside than in the middle, which causes checks or cracks, usually worse at the ends of the pieces, where the drying takes place most rapidly. The ends of valuable boards and planks are sometimes painted or cleated, which in a measure prevents this result. Occasionally, when the cleat is removed a crack will suddenly extend and even split the board.
Do not take a cracked or partly split board, thinking that you can use the sound end from the point where the crack appears to stop. Possibly you can, but oftentimes and in some kinds of wood it is impossible to tell before the stock is cut where the cracks end. In mahogany, for example, they sometimes are found to extend, or develop, several feet beyond where they appear to stop. Sometimes you can buy wood with such defects at a discount. Unless you are sure, however, that there is enough sound, clear wood outside of the cracks or knots, and unless the discount is pretty large, it will usually be better to buy clear, sound stock for nice work, as the waste is very apt to offset the saving, not to speak of the extra time and labour it takes to work up such material. (See Shakes in [Appendix].)
Reject sapwood as far as possible, because it is usually inferior to the heartwood.