Roasting Maple at Home

[davegardner0]

Here's the brainstorm of the day from me:
I'm thinking about trying a neck build at some point and would love to use torrefied maple. I know it can be purchased online from StewMac, etc., but I wonder if "regular" maple could be baked at home to achieve the same dimensional and environmental stability?

I saw a few good discussions online:
https://www.lumberjocks.com/topics/52092
http://www.tdpri.com/threads/anyone-try-to-roast-wood-at-home.567051/

Seems like the basic recipe is to bake the wood for 3-4 hours at 360F and then let it cool slowly. And based on the results people have posted, it seems like the wood darkens throughout and smells correctly. But, I wonder if they are also improving the stability through temp and humidity changes like we see with the Warmoth roasted maple necks?

A home oven could definitely deliver the needed temperature. But, when I read about torrefaction in the past I remember seeing that it must be done in an inert atmosphere like pure nitrogen or a vacuum. Obviously in an oven at home it'll be in air, I wonder if the oxygen makes the process go differently.

Anybody ever tried this or looked into it?

 

[aarontunes]

...when I read about torrefaction in the past I remember seeing that it must be done in an inert atmosphere like pure nitrogen or a vacuum. Obviously in an oven at home it'll be in air, I wonder if the oxygen makes the process go differently.

At that temp, for that length of time, I honestly don't know what would happen, but I can't imagine any way that introducing oxygen into the mix would not change the results. You may want to Google "fire triangle", and wear goggles. You can relax and read some Ray Bradbury while you wait to see what happens.  :icon_thumright: 


It looks like the guys in those links have had success with home ovens though. If you try it, please report back!

 

[bagman67]

Leaving aside the question of potential ignition or scorching of the material, I should think you'd want a chunk of lumber large enough that you can redimension it down to a normal neck blank size in the event it warps or twists or otherwise distorts in the heat.

 

[Cagey]

I'm not sure why - something to do with chemistry - but I think you need an inert (oxygen-free) atmosphere for it to work.

 

[bagman67]

I went off to do a little reading, and as far as I can tell, the oxygen exclusion is to inhibit combustion.

 

[rgand]

You can fire harden wood by leaving it in coals long enough to heat it but short enough so it doesn't start to burn. I suspect that baking it in an oxygen atmosphere would probably start the burn process a lot sooner than otherwise. That doesn't mean it wouldn't work, it just means you'd have to keep it from reaching the combustion temperature.

I did a little research and the Argonne National Laboratory says wood burns at 451° F (233° C) but there are other factors involved and some woods burn anywhere between 374° F (190° C) and 500° F (260° C). It would appear that setting your oven at 360° F is safely below the lower temperature of this spread.

 

[davegardner0]

Everybody is saying it'll catch on fire, and that's exactly what I thought would happen too. So that's why the discussion threads I linked to have me so baffled and surprised - those people posted before/after photos where the wood clearly didn't ignite. Seems like it shouldn't work but people say it does.

I have some nice tight-grained hard maple - I may just need to try it on a scrap and see what happens...

 

[spe111]

Seems like 360 would keep it right on the edge of catching on fire.

 

[Pelagaard]

Possible inferno notwithstanding, how big is your oven that you can fit a neck blank in there?

 

[davegardner0]

You can fire harden wood by leaving it in coals long enough to heat it but short enough so it doesn't start to burn. I suspect that baking it in an oxygen atmosphere would probably start the burn process a lot sooner than otherwise. That doesn't mean it wouldn't work, it just means you'd have to keep it from reaching the combustion temperature.

I did a little research and the Argonne National Laboratory says wood burns at 451° F (233° C) but there are other factors involved and some woods burn anywhere between 374° F (190° C) and 500° F (260° C). It would appear that setting your oven at 360° F is safely below the lower temperature of this spread.

I just looked into the same data, it looks like the ignition temp of wood is higher. But of course your first paragraph is my whole big question - does baking the wood in oxygen still work or not? Sounds like it's not so easy to find out!

 

[davegardner0]

Possible inferno notwithstanding, how big is your oven that you can fit a neck blank in there?

Well, the whole reason I had the idea is that I had a guitar neck in the oven yesterday, trying to bake out a warp. So I think a guitar neck blank would just fit, although I think a bass neck blank would be too long.

 

[Rick]

Yes montag,
Do it! :turtle: :bananaguitar: :evil4: :blob7: :hello2:

 

[davegardner0]

Well I couldn't help myself, I baking some scrap wood last night!

I had a scrap of hard maple 1x2 from home depot, and I cooked it at 360F for about 2 hours. No combustion! Most of the recipes I saw online said to cook it for 3-4 hours but I didn't have enough time after work.

It really smelled strongly while cooking! And the smell was very similar to how the warmoth roasted maple necks smell. The baked wood looks kinda right too, it definitely darkened but I'd say it's more grey/green and less brown than "real" torrefied maple is. It has one splotchy section too, although I wonder if that was just stuff on the surface as I didn't do any sanding/surface prep. And I didn't think to see if it was twisted at all before baking so I can say if it warped more.

Unfortunately I don't think I have a way to test it further...

So I'd say baking at home is probably pretty useful for general woodworking where you're just looking for a darker look. And I wonder if the exact color/shade could be tuned by changing the time/temp of the process. But the jury is still out as far as using it for music woods.

For these photos I tried to keep the lighting very consistent between the before and after. The baked wood is definitely more grey/green and less brown in person though.

Before:



After:

 

[spe111]

Did you weigh it before and after?

 

[davegardner0]

Did you weigh it before and after?

No, I don't have a scale more accurate than a bathroom scale. That would have been good to do though...

 

[Ninja00151]

The big issue with "roasting" in general is that there are a variety of methods, each with it's own strength and weakness. A even greater issue is that the end product quality is determined by a large number of variables, mainly temperature and time.

I haven't delved too deep into the research, but it's evident that improper "roasting" can reduce woods strength. There are different ways to measure this.

Ideally we could find an ideal process, time and temperature which results in an increase in all measurable dimensions (stability, MOE, MOR, ECT) without any detriments.

I haven't yet found any clear evidence to a clear cut best formula, but I do believe that this study is a great start for DIY'ers.

I believe that the oil process is probably the best experimental method for DIY'ers. Just by submersion of wood into oil, you've already eliminated the variable of oxygen/environment. Then you can focus on time and temperature.

This study is a bit broad. I wish it had more specific details. Alas, it alludes to an optimal temperature of 180-200°C. We have to remember that consumer thermostats aren't exactly precision devices, and I believe that using a temperature setting of 190°C will be optimal. It allows for a maximal margin of error while still being in the goldilocks zone.

Then we just have to experiment with the time domain. Increases in dimensional stability seem to be guaranteed, so in my opinion we should really focus on maximizing MOE and MOR, while decreasing brittleness. MOE to weight ratio seems directly correlated to the quality of tonewood, so any process which creates a decrease in MOE is the wrong process to use for instruments, in my humble opinion.

MOE and MOR should be pretty easy to test with a simple jig. You just need a way to secure a piece of wood, then apply pressure to it via a car jack with a pressure sensor between the two. Then record wood deflection vs pressure (MOE), and maximum pressure before breaking (MOR).

https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.thermallytreatedwood.com/Library/Technology/Germany.pdf&ved=2ahUKEwi9o67E44ThAhWNxIMKHbR-A3wQFjACegQIAxAB&usg=AOvVaw2NQZ93ni1_cFc6VIQiZxat&cshid=1552674759011

 

[Ninja00151]

Some other ideas. From superficial research it seems that brittleness is directly correlated to treatment time. We have to question why 4 hours seems to be the industry standard, and I'm sure with experimentation we can find out why- or if there is a more optimal time for our purposes. The only thing that I can think of is the possibility of penetration depth of the treatment. Just like a steak's center takes more time to cook than the outside. If that is the case, it is possible that the optimal time depends on wood (blank) thickness. With thinner blanks having a lower optimal time than thinner blanks.