Torrefied wood

[ozwood]

Hi all,

This is from the Stew mac site, Torrified timber , supposed to sound better

I Immediately went up to my Stash in a bathrobe and flashed my naked being at my timber, now it's terrified.

Came back and read further

"About torrefied wood

http://www.stewmac.com/Materials_and_Su ... uitar.html

It takes years for a new guitar to break in, to develop its tone and realize its full potential. As tonewood ages, its cell structure goes through changes, becoming much more resonant and responsive. After a few years, you get the payoff: you begin to hear the sound of a vintage guitar.

With the introduction of torrefied woods, professional builders are giving their guitars a head start on tone. The wood is heat-treated in an oxygen-free kiln, making it highly resonant and extremely stable. It's as if the wood is pre-aged. It looks and sounds like wood that's been broken in for many years."

Thoughts ? ..... about the process , not me terrifying my timber.

Cheers,

[Craig Bumgarner]

I think of the process as aging the wood, but this isn't the same as breaking in is it? I think of breaking in requiring vibration and playing. Still, the idea is interesting and I'll probably give it a try. They talk about the color and I wonder if that goes all the way through.

[hooked]

Having read about the process some time ago. The torrified wood wont take on moisture which is a plus.

Cheers

Daryl

[curly]

The process of ageing in timber is mysterious , I haven't seen a single study in all my trawling that can quantify the mechanism by which it happens ( any leads out there ?) . The lack of data is understandable as the samples would need to be analysed across such a long period of time .
One thing that would seem certain is that oxidisation would be one of the drivers of this change . A no oxygen kiln would not replicate that part of the changes . As to high temperature the positive effects could be driving off or crystalising within the cell ' oils , resins and other extractives that may have a damping effect . High temperature to the extent of discolouration will generally result in a decrease in strength , the timber will be more brittle .
They may well be getting tonal improvements , or then again it may well be driven by mill throughput . Waiting for timber to dry is a pain !
Pete

[DarwinStrings]

There has been a fair bit of discussion on the AGF with reports of improved stability, improved stiffness, more brittleness and problems with gluing it.

I have to wonder how much "older" it makes the wood but as a small builder (not like Martin or Taylor) if you look around you can still find old wood anyway. I got some lovely old stuff out of a bridge from Brent Cole with a top tap and some random bear flaw. He also just got a stack of old barge timer (cut in the 70's) and some more old bridges. Check out his Facebook page for photos of some of the collection he has done with helicopters, interesting stuff.

[Craig Bumgarner]

I ordered one from Stewmac, I'll report back, should have it tomorrow.

[Nick]

I ordered one from Stewmac, I'll report back, should have it tomorrow.

Taking one for the team Thanks Craig, be interested in your observations/thoughts. As I get older I find myself getting more and more sceptical about lots of things in life ( ) & my Snake Oil meter goes off the scale with alot of these sorts of claims.

[kiwigeo]

Oh dear....this could put Tonerite out of business

[timbuck]

I've used baked Maple for fretboards same as Gibson guitars..the dark colour goes all the way through.

[Craig Bumgarner]

Received the torrified sitka spruce top from Stewmac. Color is very nice, old looking. Color seems even all through.

I'm no big expert on judging tops, but have been using the target thickness procedure from Trevor Gore's design book (4-60) for about a year now. This top compares well with the best tops I have used in the last year since I started using 4-60. I don't think that says anything about the torrification process, but based on 4-60, I'll certainly build this top up to see what it will do.

[johnparchem]

I got a Red spruce Torrified Top from Blues Creek Guitars. I plan on using it for a steel string. It does have an old dark look to it.

I also did a 4-60 thickness calculation, and found that it tests as an above average plate for red spruce. Density not bad and stiffness looks goo as well. Here are the results.

[Nick]

Thanks for the observations guys, it would appear at first flush that there could be some advantages to this stuff .Thanks John for the empirical data, you say it seems to fit in the 'above average' bracket. For somebody who's never taken these sorts of measurements but can appreciate charts and numbers, what would an 'average' set of values look like?

[johnparchem]

I do not have enough of my own data to say what is average but the Wood Database for red spruce says 435 kg/m^3 for density and 10.76 GPa for Elastic Modulus. This wood is less dense 408 kg/m^3 and a bit stiffer 11.21. I do not know what the pre cooked values are so I do not know what sort of change there was.

[printer2]

There are three parts to wood, hemicelluloses, cellulose, and lignin. Think of lignin as the glue, cellulose as the glass fibers in fiberglass, hemicelluloses as sort of filler. Not completely accurate but good enough for a short explanation. The hemicelluloses is what is removed when torrefied tops are made. The wood is baked above 170 C and the hemicelluloses is converted into carbon dioxide and water.

Because some of the wood is lost there is less material to carry a load so the wood does not have the strength it originally had. It is stiffer and should have less dampening with the loss of the filler which gave the wood some flexibility. Wood is more flexible when it has a higher moisture content, the hemicelluloses is the main reason the wood expands and contracts with different moisture levels. With the loss of hemicelluloses the treated wood is more dimensionally stable. Gluing is different than with untreated wood. Water based adhesives in part bond with the hemicelluloses, finishing is also different.

Old wood loses hemicelluloses on its own but you need decades before you have a noticeable change. This heat treated wood is not the same as old wood but it does get some similar properties. Better to think of it as a different material. I did a cheap and dirty experiment torrifying a piece of spruce, did not know how long to bake it. Made a quick tensile test setup to see how much it changed. Measured it before and after, also measured an un-baked piece as a control. Not a great change in stiffness but it was measurable. Might take another look at the process in the future.

[kiwigeo]

Alot more logical reasoning behind this than other "aging" processes/devices.

[curly]

A question for Printer2 ;
Please don't take this as a dig . It's not .
You say " Old wood loses hemicelluloses on it's own but you need decades before you have a noticeable change "
Where is that change referenced from ? The data behind that would be fantastic to explore >
It's a real area of interest for me because none of the conventional references such as Dinwoodie or Wilson and White cross the topic of non destructive ageing of timber .
Very high temperature kiln schedules are being developed for a range of applications in contemporary sawmilling. Largely it's for increased durability . The free availability of carbohydrates being what the fungi or bugs come for .
Broadly timber is taken as being comprised of holocellulose , lignin and extractives . Holocellulose is a broad term encompassing the ( crucial to cell wall )cellulose and the molecularly smaller but also carbohydrate comprised hemicellulose .
Hemicellulose doesn't fall into the usual range of extraneous materials ( commonly referred to as extractives ) as it is bound within the essential structure of the timber . As such it being driven off in the kiln process is a significant alteration and would need to be carefully controlled !
I'm not a naysayer for the technique and carbonising of essential sugars is likely one of the changes occurring . I can see serious potential for timbers such as Huon Pine that have such a large percentage by weight of extractive materials that are likely to have a dampening effect on soundwave transferral .
I'd love to see some more research on the topic . We might have to do it ourselves !
All the best .
Pete

[printer2]

A question for Printer2 ;
Please don't take this as a dig . It's not .

No offense taken. I used to be on a forum that discussed religion, politics and other topics that get people all riled up. After a while the moderators invited me to be one of them as I did not get my nose bent out of shape when things got hot. Asking for information is not something I think of as a dig.

You say " Old wood loses hemicelluloses on it's own but you need decades before you have a noticeable change "
Where is that change referenced from ? The data behind that would be fantastic to explore >
It's a real area of interest for me because none of the conventional references such as Dinwoodie or Wilson and White cross the topic of non destructive ageing of timber .

Wish I could remember where I came across that. I have been looking at papers and articles on heat treating, bending, aging of wood and save some of the information for later viewing. I did a quick look through the titles and nothing jumped out at me which it was in. One paper that deals with it is 'CHEMICAL CHANGES IN FIR WOOD FROM OLD BUILDINGS DUE TO AGEING', searched for it and found the link.

http://www.cellulosechemtechnol.ro/pdf/ ... .79-88.pdf

While searching this one came up again also.

Some Aspects of Wood Structure and Function

http://www.nrinstruments.demon.co.uk/wood.html

Have only skimmed these.

Effects of ageing on the vibrational properties of akamatsu (Pinus densiflora) wood

http://www.u.tsukuba.ac.jp/~obataya.eii ... SK2011.pdf

Characteristics of aged wood and Japanese traditional
coating technology for wood protection

http://www.citedelamusique.fr/pdf/insti ... nglais.pdf

The Effect of Mechanical Loading on Conservation of Antique Violin

http://www.woodculther.com/wp-content/u ... li-carlson

Saved this link for when I desire some late night reading.

https://www.google.ca/search?q=http://w ... uploads%2F

http://www.amjbot.org/content/93/10/1439.full

What do we know on " resonance wood " properties?

https://hal.archives-ouvertes.fr/hal-00811117/document

Wood Science for Conservation of Cultural Heritage

'Effects of ageing and heating on the mechanical properties of wood. “ 16 ..... of wood, and therefore, quality instruments are usually made using aged wood. In this ... cohesion is weakened by the degradation and the loss of hemicelluloses.'

http://www.oapen.org/download?type=docu ... cid=343706


Sorry for the hodgepodge of articles. Wish there was one source for the information we want, would spend less time searching for stuff.

Hemicellulose doesn't fall into the usual range of extraneous materials ( commonly referred to as extractives ) as it is bound within the essential structure of the timber . As such it being driven off in the kiln process is a significant alteration and would need to be carefully controlled !

Part of the reason I have been looking into it. Also looking into creep and bending of woods. Looking into plasticizing of wood, in a couple of years I may understand this stuff.

[curly]

Much thanks for the links .
For those with an interest in timber anatomy and the effects heat treatment there is some great info to be had . Particularly recommended is the Eiichi Obayata article in the last link provided .
It explains the chemical structural changes well though I find much there that hazards caution . In short my caution could be summarised as accelerated ageing of timber could well cause a shorter lifespan for the instrument built from it .
All the best .
Pete

[printer2]

The more I read the more I am inclined to let the wood naturally. Mind you I have not tried a treated top. Will have to do one yet.

[Nick]

Was just watching one of those "factory tour" vids of the Rickenbacker factory and the guy was going on about the dark stripes in their guitar necks (which have been a feature of their guitars for years). Due to his accent I thought he'd called it 'rutified Maple' but it turns out, after a little digging/research, that it's actually "Retified Maple" . Here's a paper produced about the retification process:
http://www.thermotreatedwood.com/Resear ... cation.pdf
Just wondering what the difference between this process and the new 'wonder' treatment that is Torrefication, is? On first flush (i.e a quick readthrough) it seems the two are identical. Could just be a trade name registering thing?

[kiwigeo]

Terrified wood

Scream_1893.jpg (118.55 KiB) Viewed 27642 times

[printer2]

Just wondering what the difference between this process and the new 'wonder' treatment that is Torrefication, is? On first flush (i.e a quick readthrough) it seems the two are identical. Could just be a trade name registering thing?

Seems to be. Did not have to read any further than this.

a mild pyrolysis process

Which is another way of saying torrefication.

[hepikohetaniwha]

I don't know about torrefied wood but as a hack builder I can offer a triggerfied top: