Spruce in the oven

[arrowmandolin]

Building some flat top guitars right now, and trying a pre glueing up technique a la Frank Ford----spruce in the oven for about an hour @ 200deg.
I was sceptical, but I swear I can hear a much clearer tap tone response afterwards. It's got me thinking: A] what the heck is really going on? B] Has anyone tried this with archtop wedges?
Seems to be more evident with Sitka, don't notice much change with Red or Englemann.........

[Spruce]

There's a lot of boiling of wedge-cut billets going on in the violin world...

One recipte calls for boiling the wood for 5 weeks...

[arrowmandolin]

Thats interesting, add a few carrots and the spruce will be pre stained.

[John Zimm]

Put a little pumpkin in there and you have an early Gibson. http://www.mandolincafe.net/iB_html/non-cgi/emoticons/smile.gif

-John.

[peterbc]

I heard Frank Wakefield baked his Loar...

[amowry]

There was a discussion about this on the musical instrument makers forum (mimf.com) about this a month or so back, but I can't remember what the consenus was. It might still be there somewhere. I believe that someone heard that one of the major manufacturers was doing this.

[austin]

I am not so sure that only an hour would make much of an appreciable difference in tone, but who am I to say...!

My guess it is primarily to get it warm enough that it retains it's heat for glueing up. Not a bad idea really, since with a hair dryer the joint edges seem to cool off pretty quickly and the glue gels unevenly.

my .02!
-austin

[arrowmandolin]

Collings & Taylor both use the oven method for spruce to dry pitch and pre shrink to simulate/heat stress that may save them warranty work in the future.
It's not really a glueing technique, in fact I can see that I'll have to rejoin the joint.
What I'm finding is that after an hour @ 200, the fundamental nodes move inboard and the secondaries get really clear[I've just done my 7th one, and almost exactly the same results on all 7]
I'm amazed by the "aging" feel and sound difference.
by the way,all this sitka was cut in 1973-84

[Darryl Wolfe]

Someone told me or posted (I think maybe it was "SPRUCE")..to put the wood in a black plastic bag in the sunlight for a few hours just prior to glueing. #This gets it a bit dryer (like the oven) and the moisture condenses on the bag

[Spruce]

Yeah, that was me....
This is a great way to safely put a final cure on a piece of wood...
Here tis:

"An excellent way to artificially season wood is to use a black garbage bag.
This is especially useful for larger pieces of wood...say, a cello neck...
Put the wood inside of the bag and stick it in the sun. #Important! Seal the bag...
Let it sit for a few hours, then turn it inside out to evacuate the moisture. #The small volume of the bag will insure that the wood will not dry too quickly and crack, or case harden...
This method is great for a "final cure" on pieces of wood that you're not sure of how much moisture is still in them..."

[Michael Darnton]

I wonder how quickly the factories use this heated wood--do they give it a chance to rehydrate to a normal stable level? When I was making guitars I got the great idea to let a top roast on the car top in the sun, because it was summer and humid. After leaving it there for a couple of hours I ran it inside and glued in all the bracing. Eventually the wood went back to a normal humidity, and the top was a mess of little pillows sticking up between braces, looking like a tufted matress.

I suspect a lot of the tonal change is humidity-related--a dry sponge makes a different sound than a wet one.

Landola guitars in Finland is really baking their wood--go to their website, http://www.landola.fi/ , and look at the "thermo wood" link.

[Spruce]

Welcome to the Café, Michael....

You could smell the wood boiling all the way over at Maestronet, eh?

I'm sure you've got some good stories about cooking wood when the moon is in Feces, no?

[Michael Darnton]

Oh--I'd rather talk about other people when that topic comes up. Violin makers would never use anything other than virgin Alpine spruce, cut 100 years ago from the left side of the hill. In the dead of winter. Without power tools. After being tapped to ascertain musical value. With other appropriate, and of course, secret, rituals.

[WoodyMcKenzie]

One factor to consider when heating wood is that there are three major components to wood: cellulose, hemicelluloses, and lignin. The lignin is a randomly linked polymer that serves as a "glue matrix" to hold the cellulose fibers together. Some people call lignin "creosote" when they see it oozing out the end of a stick of wood or log lying in a fire. The point to consider is that lignin will melt before it burns (it actually is considered to be a glass, I believe), so if you heat wood # #then the glue that holds the fibers together can actually flow. Therefore, heating wood really could cause changes in the physical properties of it. My guess would be that it might release internal stresses and perhaps even stiffen it a bit. Violin luthiers bake #
bridges #to improve their performance and #I believe even some bridge manufacturers do this as well. Me, I just throw'em in the microwave! #:-)

Woody

[GTison]

R.Q. Jones of resonator guitar fame, used a microwave to "cure his wood or the whole guitar.
this was to improve the sound. He had a very large microwave for the purpose. I've envisioned putting my mando in the mic for a while. ..."DING" it sounds just like a loar. ha!

[Michael Darnton]

So, Woody, at what temp does it melt, and when does it burn? The Landola process takes it up pretty hot!

[Ted Eschliman]

Patty cake, patty cake, baker's man...
Bake me some spruce as fast as you can.
Tap it. Roll it. Mark it for Paul's "G."
Put it in the oven for, uh... Jethro and me.

Sorry, kind of lost in memories of my daughter's toddler years...

[WoodyMcKenzie]

Here is some info that I found on a wood properties website. From looking at what happens in a hot oven, it makes a difference as to whether the wood is dry or not. If it has lots of moisture in it, then you are likely to weaken it. Taking seasoned wood and placing it in a hot oven should cause the lignin to "flow". My guess is that it might tend to coalesce, resulting in a more stiff but perhaps open cell structure. This is pure conjecture on my part though. It would certainly be easy enough to test whether or not heating a piece of spruce would increase it stiffness.

****************************

Temperature Effect

* increases in temperature
* causes decrease in wood strength at a given moisture content
* interactions among temperature, time, pH determine overall wood strength
* temperatures > 150oC, hydrolysis of carbohydrates occurs, forms acetic acid
* lowers the pH
* weakens the wood


* glass transition temperature
* cellulose never reaches the glass transition temperature during pulping
* glass transition temperatures of wood components when wet:
* hemicelluloses
* 50-60oC


* lignin
* 90-100oC (130-190oC when dry)


* cellulose
* 230-250oC

[Michael Darnton]

Thanks--interesting...

[Fretbear]

Just a note about that R.Q. Jones dobro (at least the one that he made for Jerry Douglas) Jerry said that Rudy had put the wood in the microwave for very short little blasts again and again over an extended peiod of time, not all at once. Just in case anybody gets any bright ideas about their already constructed mandolin, no metal of any kind must ever be put in a microwave oven.....

[sledge]

Fretbear said, "Just in case anybody gets any bright ideas about their already constructed mandolin, no metal of any kind must ever be put in a microwave oven.....

Hmm, I wonder why Whirlpool gave me a metal shelf for my microwave? It comes with warnings about using it only when placed in the holders and to never let it touch the sides of the microwave. I've never put it in but it is stainless steel.

sledge