Torrified spruce tops

[Len McIntosh]

Recent visit to Nazareth picked up the new catalogs and there are several limited edition models that include in their description Torrified as follows;
Torrified certified European spruce in a 14 fret grand concert
Torrified Sitka spruce in a dreadnaught
And Torrified Swiss spruce in a 12 fret grand concert
Each are limited editions
Each photo shows a spruce top that is clearly altered in appearance, as if the wood was flambayed. One model is on the cover of their general catalogue.
Well I googled Torrified and it's a real word.
Anyone have info on the process and the effect on the spruce and the resulting instrument? The photos in each case show a top that is quite distinctive in appearance.

[Michael Lazar]

This is very interesting. Many luthiers (including myself) have been baking top wood especially wood that may not have been seasoned for a long time. This usually involves clamping the wood between slats (similar to stickering) and baking it for an hour at 200 degrees. During this process some of the resins are cooked out and crystallized. The wood does not change color. It looks like the torrification process involves higher temperatures (300 degrees). I also read that pressurization and an oxygen free environment may be involved.

[Randy Roberts]

While there is usually so much unsubstantiatable hype about any "new" discovery in the guitar world, this does seem very interesting.

Some research done at Guelph related to torrification for improving biomass fuels does seem to, as a side note, show some things happening to the wood substrate that would be advantageous in top woods.

I also have baked my tops for the past ten years or so at around 230 F (43 C), but that is obviously not the same as this[750-1000 F (200-300 c)]. The point was based on driving off free water in the top, leaving mostly only bound water.

With torrification, the apparent effect of turning the wood hydrophobic rather than hygroscopic is definitely intriguing, as is the loss of VOC's and some of the hemicellulose, which is what I would think could be occurring in normal tops as they age, only dramatically more slowly.

The loss of mass and increased "brittleness" might well be benefits also.

Would love to hear one, but not worth 10 grand to me to do so.

http://www.google.com/url?sa=t&rct=j&q= ... bs.1,d.cGE

[Clay Schaeffer]

200 Celsius is actually slightly less than 400 F. There was a long discussion on torrefaction on the OLF. An experiment I have thought about trying , but haven't yet, is wrapping some tops in tin foil, sealing it fairly well to exclude additional oxygen, and baking it in a gas grill.
From my limited understanding of the process guitar tops would be baked at the lower temperature end of the torrefaction process. Lignin and cellulose start decomposing at temperatures above 250C. We really don't want to end up with biofuel. The loss of hemicellulose is what I also find intriguing. There may be some advantage to having tops with semi-demi-hemicellulose content.

[Randy Roberts]

Boy did I screw up... I took the temperature conversions from a conversion chart that had been mislabeled and never had common sense kick in the whole time I was writing that. You just can't trust autopilot these days.

That does bring this down into kitchen "lab" range.

[Clay Schaeffer]

"That does bring this down into kitchen "lab" range."

I thought about using the kitchen range, but my wife keeps birds, and off gassing VOCs could possibly pose some risk to them ( or at least to marital harmony) so the less controllable gas grill might be my only option. If a person could find a sealable container that could stand the heat, displacing the air with argon ( they use for shielding mig welds) might reduce the chance of unwanted combustion.

[Randy Roberts]

Clay,
As a vet I'd say don't do anything in the house with birds there... don't even fart. As a married man I'd say don't even think about using her oven if she's in town.

My concern with the grill would be uneven heating, but if you could get a couple steel or aluminum plates, and put the foil wrapped wood between them to even out the heat, I think it would be worth a shot to try.
I would think the off gassing of the VOC's might cause a positive pressure inside the foil and maybe prevent the influx of what little oxygen might leak through the folds closing the foil?

[Steve Denvir]

Apparently, Dana Bougeois has done a lot of research and testing and he's convinced it works.

[Matthew Lau]

Strangely, my first thoughts were about the Lee Valley chisel handles.

http://www.leevalley.com/US/Wood/page.a ... at=1,41504