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My home Torrefaction Experiment...

MovinTarget

MovinTarget

Jan 30, 2018
8,333
24,872
Maryland, USA
#1
OK so I've read quite a bit about torrefaction... not everything, but enough to be dangerous.

I've bought 2 1x3x8 maple pieces from ol' HD. One because it was the straightest I could find, the other because I liked the figuring and it looked like it had some light flaming. The idea is that the latter will be planed flat later for fingerboard(s) so a little initial curve doesn't scare me.

*IF* they survive my experiments, they'll be put to use in my ultra short scale travel bass project, so I've cut both boards down to 8 24" lengths as I won't need anything longer (28.5" scale, 24 frets runs a hair over 21") and if anything, I'm not *COUNTING* on this working... otherwise it wouldn't be an experiment... Also being this short makes it easier to observe changes in shape.

Okay, each board cut in quarters so I have (S)traight 1-4 and (F)igured 1-4 with initial weights, straight after they came home and were cut:

S1: 1lbs 5.4oz
S2: 1lbs 4.2oz
S3: 1lbs 4.4oz
S4: 1lbs 4.4oz

F1: 1lbs 3.1oz
F2: 1lbs 2.8oz
F3: 1lbs 2.6oz
F4: 1lbs 3.0oz


So I find it interesting that the sets are relatively similar in weight in their F or S grouping, but that the F board, which was not as straight from the get-go seems to be lighter. This may not be related at all, but I wanted to baseline my findings before I start testing...

All 8 pieces; fairly uniform in size they looked angled for some reason...
20190219_162901.jpg

(S)straight board pieces


20190219_162941.jpg


(F)igured board pieces
20190219_162949.jpg


I will be keeping track of weight changes as I go through this, whether it is simply waiting a week or two or actually popping them in the oven.

My initial plan is to see what happens if I take HD-bought maple and expose it to different temperatures, leading up to hitting ~325f which is the target for roasting/torrefication.

I want to see if, compared to just chucking it in straight at that temperature, getting it to lose some moisture gradually (and then having some time to normalize) would reduce the possibility of warping and or cracking. I know part of the challenge is that moisture escapes from the ends faster than the sides so I want to see if I need to accelerate the drying and if doing so in phases makes a difference.

Granted this is *not* an empirical study, BUT DANGIT, I WANNA MAKE MY HOUSE SMELL LIKE COOKIES!!!!

...hopefully w/o burning it down...

So I have stowed the pieces in my attic, spaced out and I'll check in on them in a little while.

Cheers!
 
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#2
Round 1:
Boards S4 and F4 pulled from the attic and both have already decreased in weight by .1oz.

Today I will test the straight up roasting at 325F for ~4 hours.

Warming will be gradual and boards will cool in the oven to avoid sudden temp changes.

I want to try roasting them on their sides so that the "faces" are equally affected. Dunno if this is actually ideal. It may actually be preferable to lay them face down so that they "catch" more heat and let it carry through the board, you gotta start somewhere...

20190222_073308.jpg


Dunno what it is about my phone's camera but all my pics seem slightly distorted. all these boards are almost EXACTLY 24" yet they never look the same in the pics.

Oh and after taking this pic, I lined the lower grill with foil just in case anything decides to ooze out. Not sure how likely that is with maple but, they wife doesn't know this experiment is happening so burned sap would be only slightly less catastrophic than burning the house down...
 
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#8
2 hours @325F done! I think its safe to say they are darkening! Now cracks or splits visible, have to wait till finish to test for warping and cupping... Some of the visual differences are from the fact that I have foil reflecting in the below pic as opposed to the previous... But still figuring is more pronounced as far as I can tell.

PreRoast:
PreRoast.jpg


@ 2 hr Mark:
20190222_115128.jpg


@ 4 hr mark:
20190222_135132.jpg
 
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#11
I have done this with some success with a couple of nice birds eye boards.

The first worked extremely well. The second, not so much. I did not let it cool and ended up with a potato chip. No cracks, so I believe I can relax it again when I need it.

Here is the first after resaw for fretboard.

Resaw - Roast Maple Fret board

Resaw - Roast Maple Fret board

 
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#12
Okay, they are only slightly warmer than body temp so I took them out and compared them to their unbaked brethren.

I numbered the pieces as I cut them so S4 and S3 join and F4 and F3 join, you'll see them side by side so that you can see the figuring across the boards...
Torr1.jpg
Torr2.jpg
Torr3.jpg


Not as dramatic as some results I've seen but I was also pretty tame. No cracking or splitting though! Next time I might take it up to 360F or let them roast longer and see if I get better results visually.

As for weight:

They both dropped ~1.4oz (not counting the .1oz difference I measured pre-bake) so about .7oz per boardfoot of weight savings...
Torr4.jpg
Torr5.jpg


Now, shrinkage and warping:
I did not do a "before" pic but below you can see that (S)traight 4 is every bit as straight as S3, at least comparatively where F4 is more bowed than before, but still quite usable. I can easily plane that for a fretboard!
Torr6.jpg

There was shrinkage in width on both boards, nothing dramatic, but you can see the difference.
Torr7.jpg


I will upload one more pic of all the boards in a sec (both sides)
20190222_161058.jpg
20190222_161034.jpg
 
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#14
Cool experiment. Do have a moisture meter available to check the moisture difference? I wonder how long a "cooked" board would take regain the moisture as is sat unfinished. It would depend on the humidity in the room, but still that wood moisture content (before, after and well after) would be interesting data.

Isn't this just typical? You come up with a great idea and then others come up with additional points to make more work for you :)

Thanks for the experiment and sharing the results!
 
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#16
rwkeating said:
Cool experiment. Do have a moisture meter available to check the moisture difference? I wonder how long a "cooked" board would take regain the moisture as is sat unfinished. It would depend on the humidity in the room, but still that wood moisture content (before, after and well after) would be interesting data.

Isn't this just typical? You come up with a great idea and then others come up with additional points to make more work for you :)

Thanks for the experiment and sharing the results!
Click to expand...

Is this typical? Me charging into unknown territory, hoping y'all will steer me right? Absolutely! :D

No moisture meter, but i am charting weight for that reason. Supposedly, properly torrefied wood will not accept as much moisture so I want to see if they gain back weight and how much. If they get back more than .5oz-1oz, I'll assume they are not torrefied.
 
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#18
Interesting experiment. I contacted one of the very early suppliers of torrified woods who told me that after a few years of supplying torrified woods to luthiers he abandoned the process because he felt there was little benefit and the wood degraded in strength which created problems outweighing any advantages that the process offered. His kiln was supplied with a positive flow of inert gas that purged the chamber of oxygen, which he said was absolutely critical to successful torrifaction.
 
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#19
rudy4444 said:
Interesting experiment. I contacted one of the very early suppliers of torrified woods who told me that after a few years of supplying torrified woods to luthiers he abandoned the process because he felt there was little benefit and the wood degraded in strength which created problems outweighing any advantages that the process offered. His kiln was supplied with a positive flow of inert gas that purged the chamber of oxygen, which he said was absolutely critical to successful torrifaction.
Click to expand...

I don't know how I'd do an analysis of loss of strength, but I know that maple, even soft maple (which I might be using, I don't know what my Home Depot stocks), is already a very hard wood so "some" loss may not be an issue, but if it makes the maple lighter and gives it a cool look without having to get expensive... Maple may also sit in a unique position by virtue of its composition and sugar content. So I won't say this is a process that any/all woods would benefit from:



Actually this video is pretty terrible lol but you can see that the same factors will affect different woods differently.

Perhaps this is not true torrefication, but it may still be viable. I'll drop a few bucks to find out and have fun doing it. :D
 
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