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I'm considering trying some home brew torrefaction experiments. I'm wondering If wrapping the wood in tinfoil and crimping the edges will seal the wood into the requisite "low oxygen" environment and if toasting it on a gas grill on the low setting for a few hours would render the wood torrefied. It might be nice to place the aluminum foil packet between two pieces of stoneware but the frau might frown on that.
Anyone have any thoughts or information to persuade me one way or another as how I should attempt this?

how will you know what is the temperature inside the foil?

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We are all in the gutter but some of us are looking at guitars.

The only reason a low oxygen environment would be created in the tinfoil was if there was combustion occurring, and I don't think you want to end up with charcoal.

BBQ!!

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Make sure you turn it 90deg on the grill to get those nice steak house grill lines

Sounds like an interesting way to spruce up an old grill.

"Sounds like an interesting way to spruce up an old grill."

And here I was hoping it was an interesting way to grill up an old spruce......


Hi Barry,
I was thinking if I kept the foil tight to the wood it might qualify as a "low oxygen" environment. With true torrefaction it sounds like you do wind up with some combustion and charring, which is probably not what is wanted. Most of the information I can find on the net relates to the process with bio fuel as the end product. It would be nice to know more about the process being used for the guitar tops. I wonder if the volatiles leaving would push out the oxygen before combustion occurs.

"Make sure you turn it 90deg on the grill to get those nice steak house grill lines"

I guess you could then market the figured spruce tops as Bearclaw Grills tops...

I had been considering using the top of my convection oven as a heat-source except I would have to eat sandwiches during the experiments.
The convection-oven top would give me a thermostatically controlled heat source and wrapping the wood in foil would limit access to oxygen pretty well.
The barbecue sounds a tad un-controlled to me.

Bob

I was just at Costco this afternoon, and they had 8 packs of cedar planks. You could torrefy them on the BBQ, and cook your salmon at the same time.
And yes, in case you are wondering, I checked to see if they were book matched and quarter sawn.
No, and no.

Alex

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

Perfectionist!!

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Wonder what you guys think of this. Could it be used to torrofy? How long and what heat is the process?

It's a oven that has a vacuum press inside of it. The heat and vacuum is used for building composite materials. So you'd have heat and all the oxygen would be sucked out.

I can't say if tin foil will work for tops but it will work for maple fingerboards. I did some maple fingerboards a couple weeks ago. Wrapped in tin foil, in the over for a couple hours at 400 F (preheat the oven). The first time I did it, one warped so after that I put them between a couple of those cooking stones (i.e. pampered chef) and had no problems with those ones. I actually baked a couple of them twice to get darker colour. A friend of mine did an osage orange board finger board and it darkened up to a really nice colour too.

John:
How deep did the color penetrate into the wood?

Dean

Hi John,
Were the fingerboards rough sawn or already dimensioned? Like Dean I would be interested to know if the process completely penetrated the wood. Your results give me hope that the process might yield a usable end product . Did you notice any "volatiles" leaving the packet? With charcoal making they burn off fairly forcefully. That was a concern for me that made me want to use the gas grill rather than the range oven. Perhaps with the limited torrefaction there wouldn't be a significant amount leaving the packet.

I should test a piece of so-so quality rosewood (don't breathe any fumes) in the oven, in foil to see what happens to the grayish colour.

Bob

Dean

The colour went all the way through so far as I can tell. It doesn't fade going deeper. They were roughly dimensioned before cooking. I radiused one afterward and the colour is consistent.

John

This is about safety and I will tell you the fumes are not what you want in the house. TIN FOIL will not stop combustion , and then you have the off gasing.
Torryfication is a process that is a lot more complicated than heat and tinfoil.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Hi John,
Until one is familiar with a process I believe it is prudent to err on the side of caution. This is one reason my thinking turned from using an indoor kitchen stove to using an outdoor gas grill. How much off gassing will be produced by limited torrefaction is one of the unknowns, but the birds in my wife's menagerie are highly sensitive to fumes - we don't cook with teflon coated pans because of the possible toxic fumes.
Tin foil won't stop combustion, but hopefully will cut off enough oxygen to keep the wood from catching fire. With an outdoor gas grill and complete failure the worst case scenario would be a spruce BBQ, as Colin noted.
I'm sure torrefaction is more complicated than heat and tin foil, one reason I'm still in the information gathering stage of this endeavor. Most of the information I've found has been for torrefaction as a biofuel - a little farther along in the process than I want to take it. Those that use it for treating wood seem a bit more tight lipped about it, perhaps wanting to retain some mystique and voodoo for those who do.
Will it be worth the trouble? Probably not. But it's something to try. Isn't that what being an amateur, in its best sense, is all about?

Ditto, plus 1 to what John said.

Any results obtained are going to be skewed by 1) not having a full understanding of the torrification process, 2) Not being tooled-up to do the process not to mention safely as well...., and 3) The process may be somewhat proprietary to those doing it and we may not have access to exactly what they do, how long, etc.

I have another concern about the idea of torrified fret boards, especially maple. Have you ever tried to do a refret on a Kingsford charcoal briquette? Seriously, how badly will these be the fret boards from hell in terms of chipping out? I can't know but I have suspicions that for applications such as a fret board where serviceability has to remain very high, unless one is making disposable guitars.... that baking out much of the stuff that can aid in holding the wood together may not be desirable.

In an application such as a fret board who thinks that they will hear a difference (and will be willing to prove it)?

I can see torrification used for sound boards although I'm not at all a believer until I too get to see the winged horse with the beautiful naked virgin ascending into the heavens of pure tone... and I understand the desire, by some, to pursue that vintage tone. But I also see torrification being used to cut costs and if this cost cutting also makes an instrument less serviceable the value proposition, at least for cost cutting, is a trade-off that I'm personally not willing to make.

When one is Gibson.... and builds thousands of instruments annually things add up and costs are likely pretty closely controlled. Substituting crispy critter maple boards for nice, black ebony likely saves ole Henry lots of bucks (and a friendly visit from F&W as well since they are all on a first name basis these days....)

But is this what individual builders are interested in doing, making cheap instruments where serviceability may be sacrificed for the nerd who runs the company Quick Books? Sure jet black ebony is getting harder to source but I can still find it when ever I need it.

I remain interested in someone, Mikey.... trying a commercially torrified top and reporting back about the virgins on horse back.... Pics please too.... Well maybe not....

But I fail to see the point AND value of learning to make fret boards that are impostors and look like something that they are not while all the while perhaps degrading the serviceability of the resulting instrument. It's almost as bad as painting a guitar top black I tell ya....

Does anybody know anyone or have access to a heat treat oven? Its very common to purge oxygen with an inert gas while heat treating metal. Spruce tops would be a piece of cake

heat treat ovens that I am familiar with use nitrogen as the inert gas. This is not what is used in the T process. They are special ovens Some use RF some use old fashion heat but we are talking a very controlled environment.
I am not trying to be a Devils Advocate here but there is little that I have not tried . Baking a top is about the only thing you can do and this is applying heat that is above boiling point and under scorch point. 275 is a safe temp. All you are doing is chasing the free water out of the cells.
It takes considerable amount of time to get water out off the deeper wood. We are speaking of days and weeks. Still even a few hours will help when you are getting ready to glue on braces.

Here is my method

While I use a heat blanker 18 by 24 in and apply heat set point 250-275 and press flat . This forces more out of the end grain then surface. Heat for about 2 hr and cool down over night.
Then I glue the plates and braces within 48 hr. I have not had a top joint fail since doing this.

The higher the heat the more the risk of scorch.

If you smell smoke it may be too late.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I've never visited a producer of torrefied lumber, but have worked with several. There were concerns at first that it would not absorb water and could therefore prevent the use of wood glues (traditional wood glues work great with it, btw.) The typical process indeed uses nitrogen to prevent combustion while the temperature is raised slowly to values as high as 450°F and maintained for several hours to ensure the moisture content reaches 0%. It's a sufficiently involved process that I wouldn't recommend doing it yourself. It is incredibly resonant, and sufficiently stable that it could safely be used to construct instruments without a finish. I think I posted some figures before from a long term study on dimensional stability of torrefied lumber vs control samples of maple, poplar, and ash.