Drying Tropical Woods from Woodcraft

[Niels Cosman]

So yesterday I dropped by the local woodcraft to pickup a mitre gauge for my table saw and was browsing around when I got transfixed by the pile of tropical woods they have in the back of the store. You know the kind that is entombed in about an inch of paraffin.:)
I'm have been wanting to make some rosewood plane totes/knobs for a while and after the last marking knife thread, I desided that I should just make my own. Anyway, normally I can resist the temptation to buy exotics, but when I found out they were %25 off, I caved. I got a 3x8x8 chunk of rosewood (Bolivian I think)and a 2x2x8 chunk of cocobolo.

Although I haven't gotten them in the shop put a moisture meter to them, I'll bet that they are pretty wet. I asked one of the chaps who worked there what kind of moisture content i could expect, he didn't know, but said i should stick it in a paper bag or something to dry. Im wondering what the best course of action is to drying them to avoid checking.
Should I remove the wax on the sides and leave the ends sealed to acclimate?
Should I resaw to ~1/4" of the final thicknesses and seal the ends to acclimate?
Should I stick it in a paper bag? :)

Has anybody had any experience/advise with this sort of wood?

cheers,

Niels

[David Weaver]

For plane billets, I remove the wax on all of the sides and leave it on the ends. It will check, anyway. I usually buy it oversized, and for the first month or so, I go over the billet with CA glue and glue any checks that are just starting. That stops them. After a while, the checks stop developing and you don't really lose anything other than surface checking.

I guess you could try anchorseal, too - strip the wax off of all but the end and use it.

Wish I had a better answer than that, I've just about been driven nuts trying to find tropical woods suitable for making infill planes. Billets are either dry with huge cracks, or wet. The one plane I pictured here last week, i lost half the billet to cracking/checking and bug damage (that one was really really old and i got it dry - it was in wax, and it still cracked like that).

[Bill Davis]

The purpose of the wax coating is to slow the moisture sorption during transport and storage before it is obtained by the consumer. Since woods are hygroscopic moisture sorption is a forever occurance. What you need to know to be able to do the right thing is: 1) the moisture content of the piece, and 2) the average relative humidity where the piece will find its home and 3) characteristics of the species. Those determinable facts can guide you in how to achieve the best results. Without knowing its condition and its environment make it a rather 'seat-of-the-pants' decision though those frequently work quite well if you pick the right one.

Your job if you accept it is to control how the piece gets from its current MC to the equilibrium relative humidity without degrade and that depends on a number of factors such as the wood species itself and the speed you allow the MC change to occur. Some woods are able to change MC faster than others without degrade. Slower is most likely safer but its adversary is your patience.

There is lots of well researched information out there on drying wood along with multitudes of workable (maybe) 'seat-of-the-pants' methods that have worked for someone with some species and particular set of circumstances.

Best of luck (but it doesn't have to be that iffy) on turning some beautiful pieces.

[David Weaver]

My "gluing the checks" methods is something that's been used with several dalbergias, ftr, since as Bill says, there's no one-size fits all for every situation.

The dalbergias that i can recall are cocobolo, moluccan ebony, macassar ebony and what i think might be bois de rose.

Still, i did have some checking loss, though minor, it wouldn't be acceptable for 4/4 material that needed to be a tote (the totes need to have some excess thickness over normal 13/16th finished lumber or they come out thin and uncomfortable. I haven't made one from a turning blank yet, they're never oriented right to do that.

[Ryan Baker]

Scrape the wax off the sides and leave it on the ends. Then toss it back on the shelf and forget about it for a few years. (Not entirely kidding.) Rosewoods generally dry without too much drama in my experience, but it will take a while. Paper bags are another way to slow the drying, but I find it to not be much help in my climate. I expect environmental conditions are pretty similar where you are. With the stuff at Woodcraft, if it is completely sealed in wax (as it usually is), it normally will be very wet and will need a lot of drying. Sometimes you can find a piece that is only end-sealed, and they are reasonably dry.

Don't waste your time trying to measure it with a moisture meter. That won't tell you anything about the moisture in the center, which will be much higher than near the surface. If you want to know when it is dry, weigh it. When it stops losing weight, the moisture has stabilized.

[Ron Brese]

Niels,

This is a terrible time of year to expose green wood to the environment. Most places it's cold right now so many are running heat in the shop which dries out the air and in other places it's just so cold that there is very little moisture in the air at this time. Exposing quite green wood surfaces to these type environments is asking for trouble. The outer surface will dry too quickly and you'll end up with a differential in moisture content which will cause some pretty severe checking. Make sure you leave the wax on the end grain and if you take the wax off of the other surfaces makes sure you apply a couple coats of shellac or lacquer, anything to slow it down. Best bet is just to leave the wax on until the humidity is in the 40 percent range consistently.

Ron

[Niels Cosman]

Thanks for the input!

What you think resawing down to thicknesses that are closer to the size of the pieces that I will actually be making?
It seems logical that if you reduce the thickness and volume of the individual pieces they should dry faster. Although perhaps given the amount that they need to dry I would be better suited to an extra slow dry. What I really should have done is taken deep breath, put the wood down, and taken a short drive out to here: http://www.righteouswoods.net/
I have been meaning to take a field trip for a while :)

The good thing is that I am not in any hurry to use the wood and have no problem waiting for the wood to season slowly. I actually have a couple of nice 8/4 boards of Honduran Rosewood I bought from a cabinetmaker's estate about two years ago. I was told that they were originally bought perhaps 30-40 years before and they are perfect MC. I got them for around 15 bucks a bdft and have about 12 bdft (i always regret having bought more). I have been saving them for something special, but if I get super antsy I can always cut a chunk off off them.

[David Weaver]

yeah, look for a KD board anywhere you can find one. one a foot long and 6 inches wide will make at least 3 totes. One that's a full 4/4 in thickness. it's not as big of a deal if the knobs shrink some after you turn them, you can use the blanks for that.

[Jim Koepke]

Best bet is just to leave the wax on until the humidity is in the 40 percent range consistently.

That ain't gonna happen in my shop. I guess it is the curse of the Pacific Northwest.

jtk

[Brian Ashton]

I brought back a 60x13x4 cocobolo plank from Porta Valarta many years back. Long story, I was able to convince air transat to let me check it as luggage LOL... I got it straight from the sawyers yard and it was wet! I didn't wax it, I just put it in a large chest freezer I had and kept it there for years - taking it out every once in a while to cut a piece off... I had a lot of exotics in that freezer, yellow cedar log, garry oak burl, 6" thick holly..., that were just waiting for the right project. These are the sorts of wood you find once in your life. What I found over time was that they all suffered from severe freezer burn. In reality the freezer burn did nothing to the wood other than dry it out extremely slowly. When I mean dry it out, it was really dry because the humidity in a freezer is near zero. That cocobolo plank, even though it was so thick, never developed any cracks, even the pieces cut off and used. Had to get rid of everything when I decided to move to australia but! I have a piece of rare gidgee (extremely hard aus native) in the little freezer in the kitchen. Takes up a 1/3 of the freezer LOL. I wouldn't recommend it for drying large amounts but for those pieces you can't afford to loose from cracking it's been the best way I stumbled on.

[Dave Anderson NH]

One of the approaches woodturners use with green or high moisture content woods is the microwave. There are several caveats though. First one is dry at half power and for no more than 30 seconds at a time. Take the piece out and feel it for heat. If it is hot, reduce the time for the next cycle. If it is not even warm, increase the cycle to 45 seconds. Continue lengthening the cycle until you reach 1 minute or the piece is comfortably warm to the touch. Let the piece rest between cylces at least 5 minutes. Do not do over 6 cycles an hour or a dozen per day. To check your progress, measure the weight of the piece before the first cycle on the most accurate scale you have, preferably one in grams or fractions of a gram. Measure periodically after every couple of dozen cycles or every day or two. This whole thing is based on judgement and it is better to be conservative. This is the system which works for me, but you can check with some of the woodturning websites or on the turners forum and get more detailed information on this technique.

[Niels Cosman]

Brian- Ouch! your story is actually painful for ME! My sincerest condolences for your loss.

Dave- I hadn't thought about actually heating the blanks myself. It's funny how we just went from the freezer to the microwave. I actually have a small heat box that I use for curing glass epoxy. It is powered with two 40w bulbs and hangs out at 110 F with the door closed. I wonder how it would work as a mini kiln.
It's not pretty but it works like a charm for curing glue (note the ultra sophisticated ll.bean wireless digital thermal readout, the temperature is tuned using advanced analog door-cracking technologies). eat your heart out chris schwarz's arkansas insty-kiln, this hot box goes to 11! :)

179834 179835

[Montgomery Scott]

The dalbergias that i can recall are cocobolo, moluccan ebony, macassar ebony and what i think might be bois de rose.


ebony is in the diospyros genus, not the dalbergia genus.

[David Weaver]

........oops .

[Dave Anderson NH]

Niels, I would think that the low steady heat of 110F would work fine as long as you have a way of ventilating the box to get rid of the moisture. A muffin fan out of an old PC perhaps?

[Marv Werner]

Niels,

You might also go chat with the turning guys and gals. They know something about preventing cracking and checking. Not that these folks here don't, it's just that the turners deal with it all the time. They will often times rough turn a bowl for example while it's wet, coat it with some kind of solution they are familiar with, store it in a paper bag for an extended length of time, then finish turning the bowl when the wood is stable and done moving around.