Archive for ◊ September, 2018 ◊

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• Sunday, September 30th, 2018

sapele

Sapele, Entandrophragma cylindricum, stands out as significantly darker, redder, heavier, and harder than the others in this bunch. Though it would often work in the same context as genuine mahogany, I suggest not thinking of it as a substitute for the venerable old boy, but rather as a wonderful wood in its own right.

The species offers some spectacularly figured wood. Most common is the neat ribbon stripe in quartersawn boards. The striping is finer and bolder than that of khaya, and can be obtained quite reliably. The pieces pictured above are unfinished, fairly middling stuff, but the ribbon figure will pop pretty well with oil-varnish mix, and the color will deepen considerably.

Also, consider ribbon-stripe face veneer plywood, which can be found reasonably priced in a variety of thicknesses, as a nice backing for a cabinet or for drawer bottoms. You know a wood has reached all-star status when you see it as fake veneer in an elevator in a fancy downtown building.

Sapele can also produce spectacular curly figure and pommele figure. The latter is similar to blister maple, sometimes in a finer pattern. The wood is popular with instrument makers.

On the other hand, flatsawn sapele, without special figure, is a decent wood but not something that really excites me on its own. Still, it may fit the bill as a predictable, diffuse-porous, reddish wood that can finish fairly dark and will darken further with time.

No pushover like genuine mahogany, sapele is about as hard as white oak and sugar maple, and nearly as dense. It machines pretty well as long as you take precautions to avoid planer tearout on the quartered rowed surfaces and burning from ripping on the table saw. For smoothing to a finished surface, I suggest skip the handplane and go with scraping and sanding.

Sapele is about as stable as black walnut, with a volumetric shrinkage of 12.8%. The T/R is a nice 1.5, but that offers little advantage when using quarted boards for the ribbon stripe.

Shopping at different dealers, I’ve had good luck with the sapele being fairly consistent, and it has seemed safe to buy in the rough. (However, check the comment in the first post in this series – compression failures may lurk.) I’ve also found it more expensive than khaya or utile but still significantly less than genuine mahogany. It is a popular wood.

How do you pronounce it? I’d been saying sa – ‘pay – lay (like the legendary soccer player), but most often I hear sa – ‘pee – lee, and sometimes, sa – ‘pell – lee.

There’s one more post coming up in this series.

Category: Wood | Tags:  | 7 Comments
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• Sunday, September 23rd, 2018

Khaya

Next up is khaya. The wood available to us may be any of four species in the Khaya genus: K. ivorensis, K. grandifoliola, K. anthotheca, and, less so, K. senegalensis. Ask the guy at your lumber yard what species he’s selling and he’ll probably look at you the same way we look at an 88° try square, even if the importer had kept the species distinct. In fact, you’ll probably create confusion by asking for the “khaya” bin because it is more commonly referred to as African mahogany.

And so, this is the only wood comparable to genuine/true mahogany (Swietenia) that generally bears the “mahogany” name. Botanically, it is in the same family (the next major grouping above genus), Meliaceæ, as Swietenia. It comes to us from West African countries.

Just like true mahogany, when African mahogany/khaya is good, it is indeed a very good wood. The problem is that I have had just as much frustration with inconsistency in density and color in khaya as with true mahogany. There is variation among species, but also with the geographic source of the tree, and the local conditions in which it grew. Therefore, as a practical matter, I suggest that you not be too concerned with the provenance of the wood, but evaluate each board on its own merits. Khaya is about half the cost of true mahogany, and there is some great stuff available.

Some khaya is less dense, and quite light in color – an uninspiring pale pink hue. The flatsawn wood looks particularly anemic. When quartersawn, these boards often have a hairy surface that can be difficult to finish. They come off the planer with hairy rows that are hard to tame with planing, scraping, or even sanding.

I try to avoid these boards and instead look for darker, denser boards. Many quartersawn khaya boards exhibit a fairly coarse, beautiful ribbon stripe. The boards in the photo at top are a good example of dark khaya with great ribbon stripe. Look how nice it finishes:

African mahogany

More quartered African mahogany:

Khaya

The color below is a bit more red but also very nice:

African mahogany

Good flatsawn khaya is also very worthwhile. In some case, it is difficult to distinguish from high quality true mahogany. In general though, I’ve found that true mahogany’s legendary chatoyance is harder to find in khaya.

Unfortunately, khaya seems to be quite susceptible to the dreaded compression failures that I discussed in reference to mahogany in the previous post. With the possibility of these defects, as well as the great variation in the other properties of khaya, I suggest buying your boards S2S planed or hit-or-miss planed, if possible. Look them over carefully.

Coming up: sapele and others.

Category: Wood | Tags:  | 2 Comments
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• Saturday, September 15th, 2018

mahogany

Fasten your seatbelt as we ride through the world of mahogany! Our tour will be mostly about woods that are similar to mahogany, and sometimes referred to as “substitutes” for it, but are better considered on their own merits.

We start our journey with “genuine mahogany,” aka Swietenia macrophylla, big-leaf mahogany, Honduran mahogany, Central/South American mahogany, or if you want to live and buy dangerously, just call it “mahogany.” Just the name sounds, you know, classy. People, including people who buy furniture (such as you might build) but know nothing about wood, are almost always impressed by “mahogany.”

Note that in the rear-view mirror is Swietenia mahogani, aka Cuban mahogany, the best of them all, once used for building ships and furniture, but long since essentially unavailable. You might find a bit of it for sale that was rescued from the occasional tree downed in a storm in south Florida, and there is a plantation operation on a South Pacific island. I once read that it works like “cold butter,” and having had a tiny piece of the stuff some years ago, I can confirm that description.

But back to S. macrophylla. When it’s good, it has a lot going for it. Boards with good density and color are a pleasure to use in your projects. It usually planes easily on the flatsawn surface, while the quartersawn surface often exhibits attractive “ribbon-stripe” figure due to interlocked grain. This is difficult to plane but quite manageable with scraping and sanding. The wood is soft enough to saw and chisel easily but firm enough to hold detail.

The stability of mahogany is legendary. Radial shrinkage is 2.9%, tangential 4.3%, yielding an excellent T/R of 1.5, and paltry volumetric shrinkage of 7.5%.

Then there’s the chatoyance – that wonderful shimmery gleam, lovely but not overpowering – that mahogany does so well. You know, classy. A shellac and wax finish looks great.

Unfortunately, big-leaf mahogany is a big pain in the neck. Why? First, because it is expensive. I cannot find even the drabbest mahogany for less than $10 per board foot. Yet it is extremely variable in quality. Some boards in the bin will have that nice density and color, while others are junk wood – light in color and density, or often with defects. In fact, I suggest avoid buying mahogany in the rough; look for S2S or hit-or-miss planed stock.

In the photo at top, all three boards are genuine mahogany. Yup, the real thing. The top one resembles sapele (more on that in an upcoming post), the middle board is what I consider nice flatsawn mahog, and the bottom one is genuinely trash wood, as far as I’m concerned.

The most notorious defects are compression failures, sometimes called “windshakes.” These are jagged cracks across the grain, usually through the full thickness but not the full width of the board. The fibers are broken, rendering that part of the wood useless. It occurs in the tree from severe wind forces, snow loads, or, what I suspect is mostly the case with mahogany, when the tree is felled. Beware: this defect is very difficult to notice in rough boards, where it lurks to disappoint you when you bring the wood home and plane it.

compression failures

See the defect in the board below? No? Neither did I before I took it home.

hidden compression failures

Here is the other side of the board, with the compression failure clearly visible after I skimmed it on the jointer. The defect goes through the full thickness of the board.

compression failure

S. macrophylla is listed in CITES Appendix II, and on the IUCN Red List as Vulnerable. We are probably encountering mostly plantation grown wood, and the quality is uneven at best.

And so, regrettably, mahogany is nearly off my list of good options for wood. Next, we’ll look at a common alternative, Khaya, aka African mahogany. There’s that word again.

Category: Wood | Tags:  | 3 Comments