We are a small shop and make solid mahogany exterior doors with 2-1/2" long mortise and tenon joinery, epoxied and pegged through. Availability, quality and price are dictating that we make the transition from Honduras (pattern grade) to African (Khaya, straight-grained, FEQ/pattern grade - no ribbon). What I've seen of it looks indistinguishable from Honduras.
What are the implications of mixing the two in one door? They are so close in specs for shrinkage, if we select for similar grain and density, would it matter? Is it ok for paint-grade? Ok/not ok for stain grade? Do we need to try and keep the inventory separate or can we mix them thru the transition? My number one concern is/has always been quality and structural integrity and I don't want to sacrifice either.
(Architectural Woodworking Forum)
From contributor P:
I frequently mix both species, but I do so carefully. Examples like making the stiles and rails from Hondo and the panels from African. I can tell the difference between the two for most cuts, so I mix and match accordingly.
I still prefer Hondo, but as the quality and supply diminishes, African is a fine substitute. I have a few thousand BF of FEQ Hondo left, so I use it wisely, often making laminates to stretch my supply.
African seems to behave fine in service, I do not like the bigger pores and I find it had much more internal stress than Hondo. That may not be the species, but the drying. Just be sure to be honest with your customer and tell them exactly what it is you are using.
Dr. Wengert you've got me a little befuddled. I've researched your comments on mahogany and you have said that sapele and Santos are unrelated mahogany and because they look similar to mahogany have been called such by lumber sellers doing creative marketing. You said that sapele is being called African by some lumber sellers, but that there is no genetic relationship and that sapele is not African mahogany and not a real mahogany at all.
I've been researching the alternatives for some time and have compared, at least on paper, Hondu, African (Khaya), Spanish cedar and sapele. African was the closest in spec to Hondu in stability, which I've always considered the most critical characteristic for an exterior door, especially tall ones, and we build a lot of those. sapele came in last in the specs for stability. African looks the most like Hondu, so I've read, from various sources. From what I've seen so far (and I haven't seen lots of it), that's been true, though I understand there are definite variations in grades (as there are in Hondu). I've not seen sapele or Spanish cedar.
Why African? We have been using Honduras mahogany exclusively for many years. It has been a key component of our marketing and we have return customers who already have our doors. FEQ grade African seems to be the choice that would be the closest in quality, stability, appearance, color and name.
Dr. Wengert, what is your opinion about mixing the two in a single door? If the parts had similar grain and density, do you think it would be problematic?
The tree in the natural forest will reach a height ranging from 100 to 150 feet, with some trees reaching 200 feet in height Tree diameters can reach 6 feet, although 4 to 5 feet are more common.. The merchantable stem is typically straight, free of branches and over 100 feet long. As might be imagined, this large tree produces tremendous volumes of clear lumber and veneer.
As the tree is growing, the vertical cells do not align vertically in the tree, but are aligned at a small angle. In other words, the grain spirals up the tree, similar to the stripes of a candy-cane. The direction of rotation also reverses from year to year. This phenomenon is called, when the wood is sawn into lumber, interlocked grain. When quartersawn or riftsawn, this interlocked grain creates a wonderful (and desirable) ribbon pattern on the face of the lumber.
As with many imported species, this wood is subject to attack by powderpost beetles. They can be eliminated by fumigation or subsequent, prompt kiln drying.
PROCESSING SUGGESTIONS AND CHARACTERISTICS
Sapele is similar in density to red oak, but heavier than mahogany. Kiln-dried wood has a density of 36 pounds per cubic foot. Lumber planed to 3/4" thickness 7% MC will weigh about 2-1/4 pounds per board foot.
Sapele may be dried at the sawmill, but it is not uncommon to bring the wet wood to the USA for drying. It dries rapidly, but the interlocked grain results in a strong tendency to warp. This warp is best controlled by excellent stacking and low initial temperatures. Kiln schedules are similar to red oak. Overall shrinkage in drying (about 5-1/2% in width of flatsawn lumber and 3-1/2% for quartersawn) is not excessive.
Gluing and Machining
Gluing is moderately easy, but with the high density of the wood surfaces should be flat and freshly prepared. There are no resins to deal with. The interlocked grain means that on quartersawn and rift surfaces, the tool is always cutting some of the fibers "against the grain." Tear-out (torn grain, chip-out) is therefore likely, especially for low MCs and slender knives. The hook angle should be small so that the knife acts more like a plow than like a splitting chisel.
This wood moves somewhat in service when the humidity changes. Quartersawn lumber that shows the ribbon stripe will actually be fairly stable in width, requiring a 6% MC change to produce a 1% size change. Flatsawn lumber will move 1% with a 4% MC change.
Sapele is a little stronger than red oak. The bending strength (MOR) is 15,300 psi, the elasticity (MOE) is 1.82 million psi, and the hardness is 1510 pounds. Screw and nail holding is very high; predrilling of screw and nail holes near the ends of the pieces may be suggested to avoid splitting.
Color and Grain
This is the exact opposite of my experience with the other African's. They also tend to have ribbon stripe, but tear out like crazy. The last time I had to buy some 8/4 African I paid my dist to sort the ribbon out of my delivery. I like the sapele better than most of the pattern SA I 've bought in the last five years.
As far as mixing species in one door, my worry is that it could happen unintentionally, by mixing our inventory, especially shorter rail and panel stock that accumulates over time. Unless the guys doing the dimensioning are vigilant about marking every cutoff and keeping them apart, I'm worried they'll get mixed and I won't even know it, if it looks the same. Any tips on a good system for managing the inventory, especially in a smaller shop where real estate is limited? I was thinking maybe color coding?