Drying Boxwood vs. Mountain Mahogany

[Isaac Litster]

This is a fairly specific topic, but, I have heard from multiple sources that Boxwood, Buxus sempervirens which is superb for intricate carving and turning, must cure/dry for 10 years before it can be touched or used. In Simpson, William T., ed. 1991. Dry Kiln Operator�s Manual from the USDA, harder woods take longer to dry, which checks out as Box is dense, so the ~1 year per inch rule is not going to be long enough. Boxwood is usually under 10 inches, so it would, after 10 years be dry? When people carve boxwood, they include the pith, and it is dry with no cracks. How? how is it that there is a reliable method of drying an entire round/log/branch with a pith without cracking? My intuition says that it is because the bark is on it, and it dries slowly.

Now, I don't have any boxwood, but I love Mountain Mahogany, Cercocarpus ledifolius. But, I cut a tree last year, and it air dried outside with the bark on, in the log form, and it split like Pac-Man (the smaller branches <4"). Now if it dried for another 9 years, would it not continue to crack, even without the endgrain exposed? Nearby, there are dead trees that are around 3" dia, and are weathered and when cut, has cracks throughout down to the pith.

All wood is different, and on Eric Meier's The Wood Database, Mountain Mahogany has less shrinkage, but a higher ratio of tangential to radial shrinkage than Boxwood. Is that why one can be dried with the pith and the other can't? does that mean that woods with a T/R ratio of ~1.5 and less can be dried without splitting? Even more confusing for me, Red alder, which grows where I live, has (according to Meier) about twice as much shrinkage than Mountain Mahogany, and a larger ratio than Box. Still, I have seen numerous instances of entire rounds 2-7" diameter without any checking even. Obviously I am looking to dry wood without any checking, without removing the pith (as smaller pieces such as boxes and carvings using a small branch cannot be made without removing the pith). There is no way that that is possible with Pacific Crabapple, which also grows where I live, but what allows Box and Alder to be dried without any curing-related qualms?

 

[Richard Coers]

Small branches crack on nearly every species of hardwood. And especially fruitwood.

 

[Leo Van Der Loo]

! inch per year drying applies to softwood in the 2"X ??, not for thicker and hardwoods, but for 1 or 2 exemptions, like Alder and Catalpa, these have free room within the wood and so can dry without building tensioning in it.

I have turned many pieces from Crab-apple without a single one splitting, that did surprise me I must admit, most of that wood came from a large flowering and dormant tree that was being drastically trimmed.

 

[Steve Tiedman]

I am unable to comment on Isaac's post, but how significantly does cutting wood from the live plant during the peak of its dormant season help in limiting cracking, when the plant has naturally sent some portion of its above-ground moisture down into its roots?

 

[Don Wattenhofer]

In 1989 I went to a demo by Dell Stubs and the subject was thin wall goblets made from small fresh cut black cherry, then in the early 1990's I started doing vase like lidded hollow forms from the full round also. The general rule has been to use live healthy wood cut in the late fall and then rough turn or once turn before any drying has begun. The goblets and urns (vase like hollow forms) are end grain with the pith roughly centered in the small diameter base. The bowls can be end grain or side grain but when side grain usually need to be thinner to allow distortion instead of checking.

This is a goblet made from LILAC, which is very hard and must be thin including the base to prevent splits. The waste piece on the left split as shown about a day after the goblet was finished.

The 4 bowls were turned from a black cherry about 7" diameter that was almost dead right outside of my kitchen and these were turned to less then 1/8" wall.

 

[robo hippy]

Well, I dry both the same, out under tarps for a while, then inside the shop. The mountain mahogany I got was growing outside Las Vegas at 8500 feet. Only fresh cut green wood I have turned where I needed a dust mask. It does like high altitude and harsh conditions. There were 2 boxwood trees growing on my property when I bought it, 6 years ago. The bigger one was maybe 5 to 6 inch diameter. Cut them into 16 or so inch sections and stored them under a shelf in my shop. I have turned some boxes out of them and follow Richard Raffen's advice about rough turning the box blanks and then taping the bottoms together so they don't get mixed up. Almost no movement. For drying, I would suggest that you figure out what you want to do with your stock and cut into oversized rough blanks. Seal, and wait a while. For any blank over 2 inches thick, it never reaches 'equilibrium'. This means the inside will be higher humidity than the outside, which is why you will save a lot of time if you already know what you are going to do with it.

Side note, I am off to the Country Fair next week. I will be around most of next couple of days, then leave on Wednesday morning early. Come on by.

robo hippy

 

[hockenbery]

Mountain Mahogany has less shrinkage, but a higher ratio of tangential to radial shrinkage than Boxwood. Is that why one can be dried with the pith and the other can't? does that mean that woods with a T/R ratio of ~1.5 and less can be dried without splitting?

You probably understand the mechanics
The tangential shrinkage is how much the growth ring shrinks. The outer growth rings want to shrink more than the wood inside it so the wood cracks open. Smaller diameter limbs and trunks have better chances of drying without splitting than larger.
A 1/2” diameter limb of most species will dry without shrinking. 3” will be less successful.

I have dried 3” diameter holly 3 feet long with about a 60% success. These were small trees from land clearing.
Some of the failures had a foot or so of crack fee length.
I have also dried live oak balls of about 3 inch diameter
…………….………..R, T, ratio
Holly, American……4.8, 9.9, 2.1
Oak, Live ………….6.6, 9.5, 1.4

Did this ball as a demo. The wood was laying around for a while so was totally green. Also has no pith
Dry dimensions 2 15/16 x 2 12/16 x 2 10/16

 

[Hugh]

There is an "art" to drying wood where you live. It is different for everyone it seems.
If you dry your wood slowly - you have to find a method that works for you and where you live - I think you can dry wood without cracks.....most of the time.
I picked up some Mountain Mahogany years ago. 3-4" branches - cut them long and sealed the ends. Put them away in a good spot and just left them. Some larger diameter 6-7" logs - same thing and I only got one large crack along one log. Another, I brought home in a plastic garbage bag. I left it in the bag. Put it away. It dried very slowly. Seems to have come out OK. I need to find it again. Buried under a bunch of other wood now.
I am starting to like drying wood in cardboard boxes. I still seal the wood, but the boxes slow down the process. The wood still moves, but less cracks.
The thing is......friends that live 30 miles away from me.......have different results than I do because their environment is different than mine. Closer to the ocean.
I find that my Claro Walnut roughed out bowls take twice as long to dry as other rough outs.

 

[Isaac Litster]

Interesting, to complicate things, the mountain mahogany I have has been in central Oregon in a shed for the past year, where it was cut, and it has all developed a split down the length, probably exposed to too much environment.

 

[Isaac Litster]

! inch per year drying applies to softwood in the 2"X ??, not for thicker and hardwoods, but for 1 or 2 exemptions, like Alder and Catalpa, these have free room within the wood and so can dry without building tensioning in it.

I have turned many pieces from Crab-apple without a single one splitting, that did surprise me I must admit, most of that wood came from a large flowering and dormant tree that was being drastically trimmed.

View attachment 64735
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our wild crabapple cracks quickly, but only sometimes. Small pieces sometimes once turned don’t crack, tree shaped tree ornaments, and shot glasses have sometimes not cracked.

 

[Isaac Litster]

A 1/2” diameter limb of most species will dry without shrinking. 3” will be less successful.

I have heard about boiling wood in water, salt water, soaking in PEG, or even alcohol to stop or prevent cracking or shrinking. Do you have any experience about possibly boiling mountain mahogany branches of about 3”?
I was going to counter your claim, as I have a 1” dia chunk I just cut off of the corpse that has been in the elements for a year and it is split significantly down its length, but then again, it has been in the elements (-20F to 100+F) for the year.

 

[Isaac Litster]

In 1989 I went to a demo by Dell Stubs and the subject was thin wall goblets made from small fresh cut black cherry, then in the early 1990's I started doing vase like lidded hollow forms from the full round also. The general rule has been to use live healthy wood cut in the late fall and then rough turn or once turn before any drying has begun. The goblets and urns (vase like hollow forms) are end grain with the pith roughly centered in the small diameter base. The bowls can be end grain or side grain but when side grain usually need to be thinner to allow distortion instead of checking.
View attachment 64740
This is a goblet made from LILAC, which is very hard and must be thin including the base to prevent splits. The waste piece on the left split as shown about a day after the goblet was finished.
View attachment 64741
The 4 bowls were turned from a black cherry about 7" diameter that was almost dead right outside of my kitchen and these were turned to less then 1/8" wall.

I have noticed that some woods when turned thin the pith won’t split, these two are Sitka spruce branch, and Rowan, neither split, even in the base that was more or less centered on the grain and ~1/4” thick. However for items more or less solid spheres, do I have a chance? Can I boil it, and completely seal it in wax?

 

[hockenbery]

Do you have any experience about possibly boiling mountain mahogany branches of about 3”?

I have not boiled wood. Lot of folks do
I’ve turned some boiled madrone I was given. It had dried crack free and turned nicely.

 

[Dean Center]

The small amount of mountain mahogany I have harvested all dried without any cracking, with no special attention in the process. Just wax on the ends and put on a shelf in the garage. And here in the arid northern Rockies, everything with the pith still in cracks, even with wax and bagging.)

One possibility is that your mountain mahogany is actually something else. Or it could be that the southern species behaves differently than the northern species I have. (I believe Reed's (RoboHippy) MM is the southern type)

 

[Isaac Litster]

The small amount of mountain mahogany I have harvested all dried without any cracking, with no special attention in the process. Just wax on the ends and put on a shelf in the garage. And here in the arid northern Rockies, everything with the pith still in cracks, even with wax and bagging.)

One possibility is that your mountain mahogany is actually something else. Or it could be that the southern species behaves differently than the northern species I have. (I believe Reed's (RoboHippy) MM is the southern type)
View attachment 64757View attachment 64758

Interestingly, the largest species of Mountain Mahogany is Cercocarpus ledifolius, and the most common. I know that it sometimes gets black in the heartwood, to various degrees, which I saw in some I got in Utah, but also a little bit in a large tree in Oregon. Also, the trunks of the larger trees seem to have no sapwood, and from all of the pieces I have collected you cannot count the growth rings, and the heartwood to sapwood transition is completely smooth, with no star-shaped points. We probably will never know all of its secrets, as it is such an uncommon tree as far as wood goes. All of the MM I have ever seen is the curl-leaf mountain mahogany, Cercocarpus ledifolius, I don't know what Reed has, or what your leaves looked like, but I am not aware of different species that yield usable wood.

I feel as if I am doing something wrong, maybe it is where I am, but I don't know how that could be. It is in the high desert, and yet despite some of the trees I cut branches from being dead for possibly decades, they began checking within an hour of cutting, and the tree that had been cut for a year cracked even more. Because of access to sealants considering I am on vacation, I am using titebond glue, but still?

 

[robo hippy]

What I got was the curl leaf variety. It was growing at 8500 feet just north of Las Vegas. The forest service was 'clearing' for fire safety. One tree was close to 18 inch diameter, which is a monster for the mountain mahogany. It likes to grow in high and dry arid regions. At lower elevations, like 5000 feet, the juniper is the dominant tree. You never see it on the open market because it is so slow growing, and never straight, always very twisted. I think harvesting is limited in part because it is an important browse food for critters in the winter. The forest service was going to cut the stuff up for firewood. Supposedly it makes a great wood for smoking meats.

I was watching You Tube last night and saw some thing about 'splitting mountain mahogany' on some sort of log splitter. I tuned in because I thought it would be interesting to see some one try to split the stuff. Totally different wood, and not mountain mahogany at all.

robo hippy

 

[Leo Van Der Loo]

I am unable to comment on Isaac's post, but how significantly does cutting wood from the live plant during the peak of its dormant season help in limiting cracking, when the plant has naturally sent some portion of its above-ground moisture down into its roots?

It is not only less moisture in the wood, but the sap turns much more into an antifreeze, at leest that's what I was told, it's why some plants just do not freeze while others do, so some are able to survive and grow at much colder places than others.

Just found this info.

 

[Steve Tiedman]

Thanks Leo, interesting to know.

 

[Isaac Litster]

What I got was the curl leaf variety. It was growing at 8500 feet just north of Las Vegas. The forest service was 'clearing' for fire safety. One tree was close to 18 inch diameter, which is a monster for the mountain mahogany. It likes to grow in high and dry arid regions. At lower elevations, like 5000 feet, the juniper is the dominant tree. You never see it on the open market because it is so slow growing, and never straight, always very twisted. I think harvesting is limited in part because it is an important browse food for critters in the winter. The forest service was going to cut the stuff up for firewood. Supposedly it makes a great wood for smoking meats.

I was watching You Tube last night and saw some thing about 'splitting mountain mahogany' on some sort of log splitter. I tuned in because I thought it would be interesting to see some one try to split the stuff. Totally different wood, and not mountain mahogany at all.

robo hippy

Maybe, the mountain Mahogany I have gotten is at 5082 feet, and is competing with Ponderosa Pine, and little groves grow along rocky outcroppings where the Pine doesn't grow, and the juniper grows in the area but are equal in terms of distribution/competition. Maybe because it is at such a low elevation, it grows differently? I have watched nearly every video/article I can find on Instagram, Facebook, google, and YouTube that mentions any of the terms, and I have seen the video, complete letdown!