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Mark J

Roasted Wood?

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Hey @Spanky did you ever hear of roasted maple?  A guy on another forum was describing it:  

"It’s a process they do after bringing the moisture down to four percent. They pull a vacuum on the kiln and heat it to 350 degrees for four hours. That is what I was told it sure make it smell good when you turn it."

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I think this is the intentional case hardening and finish free treatment that allows raw wood to work in “rain screen” siding applications. 

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This subject prompted me to do some quick research. Roasted wood the same thing as torrefied, thermally treated or tempered vulcanized wood. As Tpt mentioned above it created a wood that is more resistant to decay and moisture changes. The process actually changes the cellular structure to the point that wood shrinkage and and expansion becomes negligible to changes in moisture. It commonly used by Luthiers for guitar necks.

Here's a quick article for DIY roasted wood;  https://www.popularwoodworking.com/nov15/roast-your-own/#

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Lee Valley uses it for some of their tool handles. They also sell small pieces of it for turning. I think they're scraps left over from the tool handle manufacturing.

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If it is case hardening, then I wonder how thick a piece of wood can be treated?  If you turn a piece and go through the "case" then you'd loose the benefit.

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2 hours ago, Mark J said:

If it is case hardening, then I wonder how thick a piece of wood can be treated?  If you turn a piece and go through the "case" then you'd loose the benefit.

If I remember right the color went all the way through, though it was only 3/4” thick.

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Sounds similar to material I have obtained from this place which is close to me. I got it for decking because I am far too lazy to treat a deck every year. With this stuff you can just leave it and it will supposedly last. Our deck has lasted about 12 years so far with no real problems. The only issue is the color, which we were warned about in advance. If you want it to keep its color outside you do have to treat it before the color fades and maintain the treatment. I didn't do that and the deck has gone from a nice brown to a gray color. I am not bothered by that but it wouldn't suit everyone.

The wood itself is a lot lighter than regular wood and apparently it loses structural strength (about 25% from memory) during the heat treatment.

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once torrefied, since all living material has been cooked, not much for modl/bugs to eat. They put it at a higher temperature than normal kiln, with the oxygen removed, otherwise it may catch on fire.

You get the benefit of ptl, without any chemical involved. And also, they can use wood such as poplar or non-economical variety, once torrefied for external usage. 

 

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I had to go find how to explain this. We do this at my day job for guitar tops on certain models. It does change the tone somewhat. I guess you need a REALLY good ear to notice just how big a change they say occurs. 
 

“The torrefaction process involves baking wood in an oxygen free environment at temperatures higher than conventional timber seasoning kilns. Taken to its logical conclusion you would end up with charcoal but stopped short, the wood merely darkens depending on how long it has been roasted.

This colour change occurs due to chemical reactions between the wood’s proteins and its natural sugars, and torrefied maple can range from soft amber to a deep reddish brown that is closer to cherry or even walnut. You can observe similar outcomes with spruce and the colour change permeates throughout the timber.“

 

Now what I have noticed is old growth “Sinker Mahogany” if you can obtain it, changes the tone drastically so that even a tone deaf person like me can notice a huge change. Go to YouTube and search Vince Gill sinker Mahogany and it’s obvious when he plays the two guitars. 
 

Back to the torrified, yes it does change the color dramatically, basically turns new wood into old wood and give it a unique smell, almost burned but still sweet. 

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@JBag09 I've heard that it is also more dimensionally stable with respect to humidity than is kiln dried non-torrified wood.  Is that true?  

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