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I have a client keen to have such a soundboard on his L-00 styled instrument so I am looking at availability. Normally I personally select all my soundboards from a couple of good local suppliers but to get torrefied wood I will have to turn to the InterWebs. So far I have found only two sources.

StewMac is selling torrefied Sitka tops which one must buy sight unseen but then again, not at a super high price.

Old World Tonewood Company in West Virgina is selling torrefied Red Spruce tops. The price is much higher, presumably due to the relative scarcity of suitable Red Spruce. On the other hand, one can at least see the individual sets and judge them cosmetically.

Who here has used torrefied wood from either of these sellers (or others)? Can you comment on the quality of the wood you received wrt grain orientation, runout, density, stiffness along or across grain, or any other qualities you'd like to mention, either qualitative or quantitative?

Thanks in advance,
Chris

p.s. If this has been covered in this forum already, accept my apologies and direct me there. I don't spend much time on this board.

RC Tonewoods and Blues Creek Guitars can supply them. I have used all four of these sources with good results. I find fish glue to work best for me when gluing braces/bridge. I had some issues with Titebond original. HHG would work as well I believe.

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"I've been had again"
Tim Benware
Creedmoor, NC

Bow River Specialty Woods, a forum sponsor sells torrefied adi spruce, and their pricing is in Canadian dollars. https://woodtoworks-com.3dcartstores.co ... _c_41.html

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

Just saying --- having a primitive understanding as to how wood glue is supposed to function at the microscopic level I find that very disturbing.

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Ken Cierp

http://www.kennethmichaelguitars.com/

Colonial Tonewoods, another sponsor with a solid reputation has them too.

http://www.colonialtonewoods.com/collec ... uitar-tops

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I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

So -- are all torrefied sound boards processed exactly the same way? What are the specs? Time, environment, temperature? According to Martin techs (and advertising) it makes a huge difference.

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Ken Cierp

http://www.kennethmichaelguitars.com/

I've used Stewmac torrefied Sikta spruce tone wood and braces on two guitars. The first had spectacular grain and lacing and sounded as good as it looks. The second set was not as pretty as the first, but still looks nice and sounds as good as the first.

I'm just finishing topping a guitar using torrefied Adi spruce and braces I got from RC Tonewoods. While I still haven't glued the bridge down, tapping the top on the body reveals it to have a big booming voice.

I used Old Brown Glue to joint the tops and to glue the braces. No problems at all.

Each processor has their own recipe to get what they want, different ways to skin the cat. Unless you have a good understanding of the processes the different times and temperatures will not be of much use.

So the spruce that is tossed in an autoclave along with the planks at deck lumber processing facility -- is just as good as the material meticulously processes at the Taylor and Yamaha factories to their specs or by the Martin supplier to their specs? The point is are we to just assume that all torrefied sound boards are made equal? And who has done the testing that indicates that to be true?

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Ken Cierp

http://www.kennethmichaelguitars.com/

I've been wondering about this exact point too. Unless all the suppliers of torrefied tops get their treated top sets from the same source (not likely, I think), then it's seems unlikely that torrefied tops from different sources have been treated the same way. Maybe it matters, maybe it doesn't. Based on the Martin "time machine" theory of torrefaction, it would, but I think that's a bunch of marketing hooey. If people have been happy with the tops they've used from different sources, maybe there's enough room for variation in the method that it doesn't matter.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

"The point is are we to just assume that all torrefied sound boards are made equal? And who has done the testing that indicates that to be true?"

I guess that's the beauty of the forum - you can find out who has used wood from various vendors and what the results have been. I'm still gathering data points in my beady little brain.

The exact details are contained in Yamaha's patent application for their A.R.E. process. See: http://www.google.com/patents/US6667429

The basic process is to use an autoclave that removes the oxygen and heats the wood to about 400 degrees using live steam.

A lot depends on the end result you're after. For the sake of discussion, let's assume that torrefaction 'ages' wood. So, the longer you leave the wood in the autoclave the more it 'ages'.

Martin has two levels of torrefaction, M1 and M2. The M1 wood is what's used on their VTS guitars. It is left in the autoclave only long enough to 'age' the wood so that the degree of crystallization 'matches' that of wood from the period that they're trying to duplicate, let's say 1937.

When wood is lightly torrefied, such as the Yamaha A.R.E. or Martin M1 process, the wood doesn't discolor very much, if at all. Also this wood is semi-translucent. Not as translucent as new wood, but not as opaque as 200+ year-old wood.

The torrefied wood sold by Stewmac, RC Tonewoods, Colonial, Blues Creek, etc. are more like Martin's M2 process which is in the autoclave for a longer period of time. This makes the wood darker and completely opaque.

Martin does sell one guitar with M2 torrefied Adi spruce. See: https://www.martinguitar.com/guitars/limited-editions-and-new-models/d-35e-50th-anniversary-limited-edition/

No. the time/temp is dependent on the size/thickness/type of wood.

Titebond, and many wood glues, work as follows: when 2 pieces are joined together the glue enters the grain of those pieces and when dried it is basically interlocking webs of glue that hold the pieces together...

perhaps hide glue has more of a 'sticky' effect? point being, try joining 2 pieces of wood without clamping and notice how easy they break apart...the glue itself isn't all that strong, it's all those 'webs' going into the grain structure that make a joint so strong...

in the case of torrefied woods, perhaps the grain structure has been changed in such a way that alphatic resin glues don't have as much penetration into the grain as compared to natural woods...

Not sure what I said implies the two examples of processors you give produces the same material.



Why would they be the same, we have enough variability in non-treated tops and we do not expect them all to be equal. Can we test the untreated tops and have a simple measure of their worth?

Wood is a complex material. The process changes this material. The time, temperature, amount of moisture present all change the reaction going on. One graph of torrefaction that I found.



The lower the temperature the less hemicellulose gets lost, the higher looses more. But then you start removing the other components. Given the time and temperatures that a guitar top processor uses will you be able to determine how much processing changed the wood? I would not be able to. Is there a graph comparing the processing at 375 F for two hours as compared to 385 F at one hour? The processors may have one, you and I, fat chance. At best we can compare their final product compared to other products.

I have worked in two industries where we take the raw material and cook them to change their properties. We had schedules that were found to work and followed them. That does not mean that a different schedule would not work and produce a similar result. We also sampled the material and modified the schedule if we found the raw material was different than the one originally used to set up the schedule. We also had different schedules to produce the product with a different 'flavor'.

As far as myself, I just look to see if I get the color change I want. Sort of like looking in the oven to determine if the pie is baked enough.

I have two builds with torrefied tops. I used hot hide glue on both. The tops were purchased from Stew-Mac. The first build is pushing a year since completion.The first (a small jumbo, eir S&B), sounds way better than any other build Ive completed. It was my eighth, I'm still a learning novice, for sure. The volume and sustain is notably much better than my other builds. I had read from other sources that glue absorption was a problem, and kept that in mind in these builds, but have not noted a problem. I used torrefied bracing, as well. I followed the same accepted process in using the hhg as would anyone. The second build, a slope shouldered dread, bubinga, isn't quite hitting on all cylinders, but I'm sure that it is the top thickness, and bracing size. Again, no problems with glue adhesion. The tops tend to be stiffer, so I try to thickness accordingly. Again, Im still on the uphill side of the learning curve, but from what I've seen, I really like these tops. The quality of the tops and consistency of the three I've purchased, from Stew-Mac, is very good.

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"It is easier to fool a man, than it is to convince him that he has been fooled"
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I found an article online that compared different properties of untreated wood vs. treated wood. (torrefied in an autoclave) See: http://savagelight.com/guitar/TorrefiedStrengthTests.pdf

Basically, as you found the wood gets stiffer. According to to the article, torrefied wood is about 10% stiffer than untreated wood. I found this article before starting my most recent re-top project, so I adjusted the thickness and thinned the height of the braces 10% downward to account for this. I'm in the cutting/polishing stage of finishing and I expect to have this guitar ready to play in about a week.

I, too, really like the torrefied wood, and with the wood that Stewmac is selling, especially given the low price.

Stiffness varies as the cube of the thickness, so if it is 10 percent stiffer, you would only need to reduce thickness by 3.2 percent to have equal stiffness. (i.e. 1.032 x 1.032 x 1.032 = 1.10

By the same math, reducing thickness by 10 percent will reduce stiffness by about 27 percent,
Mike

Thanks for the info, Mike. I'll keep that in mind on the next job.

Dan

FWIW, I was concerned about a torrefied top I had. I'd tap it and it'd sound like cardboard. Emailed John Hall, who's done a bunch of torrefied tops, and he said not to worry. Once they're braced and the box is closed, they sound great.

Steve