Excerpted from “Make a Joint Stool from a Tree,” by Jennie Alexander and Peter Follansbee.
If you have a number of oak logs to choose from, then you can go through the checklist of factors that affect the work ahead. Once you find a straight-grained log that’s nice and even with little or no taper, has a centered pith in a mostly round shape, and no twist in the bark – then you’re ready to work that log. But there’s one more thing. You can go even further and look at the rate of growth in the tree’s annular rings. Fast-growing oak has widely spaced annular rings, sometimes up to 1/4″ per year (see fig. 3.3, above). This timber is exceedingly strong because it has fewer rings, which creates a great concentration of the dense latewood that grows in the summer. But the resulting timber is visually distracting. Its radial face comes out looking heavily striped. It can also be difficult to work; it has an
uneven texture resulting from the widely spaced transitions between the earlywood and latewood.
The slow-grown oak (see fig. 3.4, below) is more even textured, both visually and for working. While technically weaker than its fast-grown counterpart, slow-grown oak is still well suited for joined work. This furniture is grossly overbuilt by stress standards, so the decrease in strength is not a factor. The benefit is the consistent texture, ease of working and a closer visual match to the timber used in 17th-century work done in New England. You can’t always get what you want, but if you are faced with two otherwise evenly matched logs, try the one that grew more slowly. The only thing better than riven radial oak is slow-grown riven radial oak.
The most important sentence here is this one: “This furniture is grossly overbuilt by stress standards, so the decrease in strength is not a factor.” – for instance, I wouldn’t use the slow-growing oak for a ladderback chair, say. But the oak furniture that is the subject of this & my other LAP book don’t rely on the strength of the material – they rely on bulk and drawbored joints.
Maybe its because I live on a hill a four leaf clover is easier to find than ” a straight-grained log that’s nice and even with little or no taper, has a centered pith in a mostly round shape, and no twist in the bark”. Ash seems much less wound up reducing the Axe elbow from the post riving correction
Peter, does the same generally hold true for pine? Slow growth looks better and is easier to work. Fast growth is stronger?
I believe it’s flipped around for pine (& softwoods in general), just the other way. It might only apply to ring-porous hardwoods. Time to consult Hoadley’s book Understanding Wood…
This reminds me …
of something I read years ago about the brilliant John Harrison (1693 – 1776) who was a self-educated English carpenter and clockmaker and invented the marine chronometer. In his early clocks, made of wood, he used the dense summer wood of fast grown oak for the teeth of his (wooden) gears.
There ain’t arf been some clever bastards.
Interesting (at least to me 🙂 related fact. Slow growth oak is also generally better for cooperage for aging wine and spirits. Fast growth oak has a higher percentage of summer growth (the stuff between the stripes) that is more tannic. Some tannins are good, but too much can be harsh. Slow growth oak has a higher percentage of spring wood and tends to have more aromatics (vanilla, cloves, spices, coconut, etc…).
Let’s be clear about this. Slow growth oak is advantageous for some uses, whereas faster growth is superior for other uses. Slow growth is easier to carve, and more homogeneous (and sometimes more boring) in appearance. The patterned surface carvings found on 17th century furniture will also show look better. Faster growth oak is superior when you need strength, or if you’re bending, or like to see an interesting visual growth ring pattern. Chairmaking and boatbuilding often call for these characteristics. Post-and-rung chairs require strong rungs, tough leg tenons, and strength if the rear posts are bent. Windsors also want quick grown strength for spindles, bent arm bows and leg/stretcher systems.
So, in the context 17th century joined furniture slow growing stuff is gold. But neither is a the superior material.
Note: This discussion applies to ring porous hardwoods, not other hardwoods or conifers.
Thanks, Drew – in my first comment in this thread, I pointed out that the furniture I’m building is a bit of an anomaly, “grossly-overbuilt” is not an exaggeration. Chairs and joinery don’t come from the same log, in the best of worlds. Thanks for clearing up the details.