Wood is laid down in increments on trees which may, generally, be seen and counted as annual growth rings. Although some trees may appear to have grown straight out of the ground most have some degree of spiral twist. The twist may be right- or left-handed. Timber cut from trees with left handed twist tends to open up as it ages; timber from right handed twist tends to close up as it ages. 

To insure a high degree of confidence that a pair of boards for a book are likely to remain in plane, in service, they should be split (not sawn) out from quarters of air dried wood which has right hand twist. When a tree has been felled, quartered, and cut to length, it may be split and stacked with the bark facing in and out in alternating layers to dry, as illustrated. The quarters may be likewise stacked. There are advantages with either method. Splitting the boards out soon after falling the tree is easier, but the stack must be carefully monitored as it dries. Splitting the boards from quarters which have been air dried for a few years is harder on the hand, mallet, and froe, but the quarters may be left more or less to their own devices as they season. There is a danger that the wood will become case hardened. This happens when the wood on the outside of the quarter dries before the inside, making a very tough barrier to split through.

With either method of splitting there is more firewood and kindling than book boards. The important advantage of quarter-split boards is that the splitting action follows the twist, if any, of the wood; a saw leaves all boards straight. For the moment. During times of extreme and rapid changes in relative humidity, including floods, sawn, kiln dried boards are more likely to warp than air dried, split boards.

My practice is to air dry quarters (generally of Oregon White Oak) for a few years in the garage before splitting them. Those boards which split out straight or fairly straight, are dressed down with a broad hatchet (a hatchet which is flat on one side and beveled on the other) and taken to my basement workshop for a year or so. Those which remain in plane are trued up with a small drawknife, round bottomed spoke shave, and planes, and brought down to a thickness of a quarter-inch or so, following which they are brought to the lab where they lay on a shelf for another year, or longer, until I need them. I cannot say for certain that boards prepared in this fashion will never warp or twist in service, but I do not believe that it is likely.

With the exception of the froe and some scrapers, all edge tools used in preparing wooden boards by hand have one characteristic in common; they are flat on one side and beveled on the other. The basic tools which I use in making wooden boards are a mallet and froe, broad hatchet, draw knife, curved spoke shave, skew plane, rabbet plane (for quarter-bound work), handled scrapers, unhandled scrapers, files (metal working files also work well on wood), and a variety of chisels.

Even with a tool as simple as the froe, there are two types; one for hardwoods and another for softwoods. The type which is most effective on hardwoods is thicker than that used for softwoods. Each type will work on either sort of wood, but the softwood froe, not unlike a thin wedge, is more likely to be pinched tight in hardwood. This leads to aggravation, and ultimately, profanity. With either type of froe, sharpening should not produce a facet; instead, the faces should be slightly rounded. If the struck edge has a slight crown, the mallet will last longer. Mallets should be taken from the root stock of a young tree, the size depending on the type of use (i.e., hardwood or softwood) and strength of the users arm. I like a mallet to be about 18 inches in length and about 6 inches in diameter. Remove the bark and smooth out the edges with an axe, then form the handle using a drawknife. If the handle is formed by sawing into the mallet and splitting away the excess wood with a chisel, a weak point will be created where the handle joins the head.