Changes in sound of guitars over time

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constructordeguitarras

Posts: 1672
Joined: Jan. 29 2012
From: Seattle, Washington, USA

Changes in sound of guitars over time

My customer for the Brazilian negra and I talked about the sound of guitars changing over time, when he first came to try out some guitars, and when he came to pick up his. I had no real explanation for the changes either time, but after he left with his guitar I thought about it some more and I came up with this explanation, which I sent him in an email and which I rather like:

Light colored woods, such as spruce, visibly oxidize on freshly cut or sanded surfaces, just like the inside of an apple after it is cut. I’m sure darker woods oxidize too, though perhaps the pigments in some of them act as antioxidants. That soundboard standing on my table in my workshop whose rosette you admired has been standing there for a long time and it has turned much browner than it was. This must happen to the inside of the guitar, where no finish is applied. (It also happens to finished surfaces, but more slowly. Your soundboard will darken.) Perhaps this change in color due to oxidation is accompanied by hardening—as when ancient people heat-treated the points of sticks to make spears or arrows. And the hardening would affect the acoustic properties of the wood.

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 20 2015 21:45:03

JuanDaBomb

Posts: 189
Joined: May 18 2011

RE: Changes in sound of guitars over... (in reply to constructordeguitarras)

Hi Ethan,

Well, here is my theory (and that’s ALL it is, but based on what I’ve learned from studying physics & engineering I tend to believe something like this).

When I look at an assembled guitar, I see a structure with a complicated system of static internal forces (when it's not being played that is). Of course, there are significant internal forces within the separate components even before they are assembled, but the processes of gluing, clamping, doming, strutting, and so on create an entirely new set of internal stresses because of the physical work being done to the whole. Not to mention changes in water content of the woods over time.

From what I understand, typically these stresses don’t remain constant over time, especially when work is being done on the structure (in this case the actual playing of the guitar). It gets complicated but my thought is that all these vibrations experienced by the guitar serve to relieve some of these internal stresses over time. And the result is a different, lower system of internal stresses that resists the input of external forces in a different way.

At this point I would like to now open up my explanation to being picked apart and rectally probed in true Foro fashion

REPORT THIS POST AS INAPPROPRIATE | Date Jul. 20 2015 22:57:06

constructordeguitarras

Posts: 1672
Joined: Jan. 29 2012

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Post has been moved to the Recycle Bin at Jul. 20 2015 23:57:03

REPORT THIS POST AS INAPPROPRIATE | Date Jul. 20 2015 23:53:40

constructordeguitarras

Posts: 1672
Joined: Jan. 29 2012
From: Seattle, Washington, USA

RE: Changes in sound of guitars over... (in reply to JuanDaBomb)

Juan--I'm sure there is truth to your explanation.

(I had posted a picture of someone putting on exam gloves. Decided it was inappropriate even though it made me chuckle. I should have just changed it to this post.)

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 21 2015 0:12:27

Anders Eliasson

Posts: 5780
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RE: Changes in sound of guitars over... (in reply to constructordeguitarras)

I dont think your spruce tops hardens over time. I does get prettyer though

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 21 2015 8:09:03

jshelton5040

Posts: 1500
Joined: Jan. 17 2005

RE: Changes in sound of guitars over... (in reply to constructordeguitarras)

quote:

Light colored woods, such as spruce, visibly oxidize on freshly cut or sanded surfaces, just like the inside of an apple after it is cut. I’m sure darker woods oxidize too, though perhaps the pigments in some of them act as antioxidants. That soundboard standing on my table in my workshop whose rosette you admired has been standing there for a long time and it has turned much browner than it was. This must happen to the inside of the guitar, where no finish is applied. (It also happens to finished surfaces, but more slowly. Your soundboard will darken.) Perhaps this change in color due to oxidation is accompanied by hardening—as when ancient people heat-treated the points of sticks to make spears or arrows. And the hardening would affect the acoustic properties of the wood.

This sounds like an endorsement of torrified topwood

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 21 2015 14:23:35

Stephen Eden

Posts: 914
Joined: Apr. 12 2008
From: UK

RE: Changes in sound of guitars over... (in reply to constructordeguitarras)

The colouring of spruce is also down to UV exposure and can happen very quickly in direct exposure.

Wasn't the heat treatment of wood there to bring the natural cellulose of the wood to the surface in order to protect it from the elements?

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 21 2015 14:34:17

constructordeguitarras

Posts: 1672
Joined: Jan. 29 2012
From: Seattle, Washington, USA

RE: Changes in sound of guitars over... (in reply to jshelton5040)

quote:

This sounds like an endorsement of terrified topwood.

By golly, it does, John! I just looked up "torrified," having never heard of it before and even found "torrified guitar top" among Google search choices. Well, there you have it: I must be right!

http://www.premierguitar.com/articles/21444-acoustic-soundboard-torrefied-woodsdont-be-afraid

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 21 2015 14:47:38

constructordeguitarras

Posts: 1672
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From: Seattle, Washington, USA

RE: Changes in sound of guitars over... (in reply to Stephen Eden)

quote:

Wasn't the heat treatment of wood there to bring the natural cellulose of the wood to the surface in order to protect it from the elements?

Stephen--

Cellulose is macromolecular, a polymer. So it's not likely to move around in the wood. Though I guess you could be vaporizing everything else.

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 21 2015 14:53:51

constructordeguitarras

Posts: 1672
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From: Seattle, Washington, USA

RE: Changes in sound of guitars over... (in reply to Anders Eliasson)

quote:

I dont think your spruce tops hardens over time. I does get prettyer though

Anders--

I'm talking about the very thin surface layer that turns brown. You could easily sand it off and see light-colored wood underneath.

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 21 2015 15:10:18

crooksj5

Posts: 106
Joined: Jan. 7 2014

RE: Changes in sound of guitars over... (in reply to constructordeguitarras)

I have also heard new guitars described as being "tight". This leads me towards the idea of he previous poster talking about the internal forces inside the guitar becoming more mild, maybe as vibration starts to set things in place and let them resonate uninhibited?
The torrified top thing is becoming increasingly popular with steel string guitars. When playing these guitars and nylon string guitars where the top has "opened up", one difference I think I am hearing is it makes the guitar more responsive to changes in dynamics and attack and they also seem to have a more "open" sound than a newer guitar or one without the torrified top of the same brand/model.
Just my 2 cents

REPORT THIS POST AS INAPPROPRIATE | Date Jul. 21 2015 15:11:57

Stephen Eden

Posts: 914
Joined: Apr. 12 2008
From: UK

RE: Changes in sound of guitars over... (in reply to constructordeguitarras)

Ahh yes I see it is actually the oppostie of what I said and only works on open celled timber. I only saw the process done once on a program called grand designs and could only remember cellulose being mentioned.

I've looked into it a bit more and it's actually burning the cellulose away from the outer layer of the wood leaving it charred on the out side. It seems to be a Japanese method called Shou Sugi Ban. It looks great but I don't think it will hard the wood!

There has been a few guys over on the delcamp forum talking about cooking their tops in an oven before using them. Shame I don't have an oven big enough to try it out.

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 21 2015 16:47:25

Ricardo

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RE: Changes in sound of guitars over... (in reply to constructordeguitarras)

Nah it's just voodoo, vibrations... And humidity

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 21 2015 16:58:54

keith

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From: Back in Boston

RE: Changes in sound of guitars over... (in reply to constructordeguitarras)

ethan, i am curious about when wood oxidizes how the reduced molecule is handled with respect to its affect, if any, on wood? in the redox reaction is uv light considered the accelerant much like heat is to a chemical reaction?

REPORT THIS POST AS INAPPROPRIATE | Date Jul. 21 2015 17:50:25

estebanana

Posts: 9351
Joined: Oct. 16 2009

RE: Changes in sound of guitars over... (in reply to constructordeguitarras)

The last month I've read a lot about the process of Torrefaction. Seems like it is different than baking wood.

I was curious what all the talk is about so I researched it. Torrefaction is heating wood to a high temperature in a vacuum chamber with no oxygen by using steam to heat the inside of the chamber. Several of the volatile compounds, from what I understand, are cooked out of the wood and the wood ends up being dried slowly as it is cooled and it reaches zero moisture content. Then it is re treated to hydrate it back to 4 to 6% moisture.

Look up the Wiki entry for Torrefaction, it's used in the fuel industry to create better burning wood charcoal. You may remember hearing about this process this in science class or from reading about how artists charcoal is made. It's a similar process.

"Baking" tops is is different than Torrefaction, it means the tops are actually baked with heat and a tiny bit of moisture in a big commercial oven. There is a Youtube video of the process being done at the Taylor factory. There is no steam heat or vacuum chamber.

Both baking and Torrefaction render the wood more climatically stable; the companies that bake and Torrify ( terrify) the wood today are Yamaha, Martin and Taylor and several other smaller companies. The reason they claim they process this way is better sound, but it's my guess it also has much to do with warranty. The Baked T-fied woods are more stable and less prone to cracking and failure do to climate changes.

I think the Torrefied woods have a lot to offer, I may try one of the Torrified tops. For one thing the wood strength seems to measure the same after Torrefaction, but the weight is reduced by 20%- Plus it's more stable to climate change. How can that be a bad thing?

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 21 2015 23:42:25

Ruphus

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RE: Changes in sound of guitars over... (in reply to constructordeguitarras)

Makes me speculate that Amalio Burguet (whose stock of wood is reknown for good quality) could be using this method.

For, my guitar of his has withstood the local conditions of extreme dryness (around 30% RH and often enough even lower), whilst BRW is notorious for cracking easily.

Ruphus

REPORT THIS POST AS INAPPROPRIATE | Date Jul. 22 2015 9:45:27

Anders Eliasson

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RE: Changes in sound of guitars over... (in reply to constructordeguitarras)

Do you have a list of those guitarmakers who have good and bad woods?
I was in Maderas Barber years ago and Burguet was there. We were picking more or less the same wood. He did of course pick a lot more because he has a factory while I´m only a single luthier doing everything. But I guess that this means that i qualify for being reknown for good quality as you say. Or do I have to cook, bake and fry my wood in order to be on the prominent part of that list?

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 23 2015 10:41:27

Ricardo

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From: Washington DC

RE: Changes in sound of guitars over... (in reply to Anders Eliasson)

quote:

ORIGINAL: Anders Eliasson

Do you have a list of those guitarmakers who have good and bad woods?
I was in Maderas Barber years ago and Burguet was there. We were picking more or less the same wood. He did of course pick a lot more because he has a factory while I´m only a single luthier doing everything. But I guess that this means that i qualify for being reknown for good quality as you say. Or do I have to cook, bake and fry my wood in order to be on the prominent part of that list?

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 24 2015 1:42:49

constructordeguitarras

Posts: 1672
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From: Seattle, Washington, USA

RE: Changes in sound of guitars over... (in reply to keith)

Keith--I'm not sure what your first question means. By the way, I'm no expert; the last time I had a serious thought about chemistry might have been in 1988. But there are reactions that are initiated by uv light and others that are initiated by heat. I'm not sure I've heard the term "accelerant" used for this. I have heard that wood is discolored more quickly on exposure to light, but I imagine that the oxidation occurring inside the guitar is mostly not due to acceleration by light.

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 24 2015 2:55:58

constructordeguitarras

Posts: 1672
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From: Seattle, Washington, USA

RE: Changes in sound of guitars over... (in reply to JuanDaBomb)

Juan--

I've been thinking about how a lot of change occurs in the first week or so after a guitar is made. I think that your explanation probably applies more to those big initial changes and maybe my explanation applies more to the ones that happen more gradually over the next few years.

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 24 2015 3:00:37

timoteo

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From: Seattle, USA

RE: Changes in sound of guitars over... (in reply to Anders Eliasson)

quote:

Or do I have to cook, bake and fry my wood in order to be on the prominent part of that list?

... and don't forget a pinch of salt!

Here's how we do it in the Pacific Northwest. Cedar plank grilled salmon - starts out as tapas and ends up as a tapa. It's torrefied too!

(image source: http://www.gourmet.com/recipes/2000s/2009/08/cedar-plank-salmon.html)

Images are resized automatically to a maximum width of 800px

Attachment (1)

REPORT THIS POST AS INAPPROPRIATE | Date Jul. 24 2015 3:10:30

JuanDaBomb

Posts: 189
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RE: Changes in sound of guitars over... (in reply to constructordeguitarras)

quote:

ORIGINAL: constructordeguitarras

Juan--

I've been thinking about how a lot of change occurs in the first week or so after a guitar is made. I think that your explanation probably applies more to those big initial changes and maybe my explanation applies more to the ones that happen more gradually over the next few years.

I wouldn't doubt that in the least. You guys are the experts about guitars and stringed instruments

I do think you're on to something about the surface hardening. We already know that finishes cause changes, perhaps hardening belongs in that same area of change (?)

REPORT THIS POST AS INAPPROPRIATE | Date Jul. 24 2015 7:04:31

Anders Eliasson

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RE: Changes in sound of guitars over... (in reply to timoteo)

quote:

quote:

Or do I have to cook, bake and fry my wood in order to be on the prominent part of that list?

... and don't forget a pinch of salt!

Here's how we do it in the Pacific Northwest. Cedar plank grilled salmon - starts out as tapas and ends up as a tapa. It's torrefied too!

Now, that looks yummi. I´ve always wanted to go to PNW BC and Alaska and now even more.

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 24 2015 7:26:07

Escribano

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From: England, living in Italy

RE: Changes in sound of guitars over... (in reply to Anders Eliasson)

quote:

I´ve always wanted to go to PNW BC and Alaska and now even more.

You should. I used to travel to Seattle/Redmond on Microsoft business a lot and loved it. It rains like England there

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 24 2015 8:12:28

estebanana

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RE: Changes in sound of guitars over... (in reply to timoteo)

quote:

Cedar plank grilled salmon - starts out as tapas and ends up as a tapa. It's torrefied too!

More like Salmonified. That looks tasty

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 24 2015 9:04:12

constructordeguitarras

Posts: 1672
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From: Seattle, Washington, USA

RE: Changes in sound of guitars over... (in reply to JuanDaBomb)

quote:

I do think you're on to something about the surface hardening. We already know that finishes cause changes, perhaps hardening belongs in that same area of change (?)

Right, good point (I should have thought of saying that): finishes; not to mention, fishes.

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 24 2015 11:20:20

BarkellWH

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From: Washington, DC

RE: Changes in sound of guitars over... (in reply to timoteo)

quote:

... and don't forget a pinch of salt! Here's how we do it in the Pacific Northwest. Cedar plank grilled salmon - starts out as tapas and ends up as a tapa. It's torrefied too!

A few years ago I was in Astoria, Oregon on some business and had some cedar plank grilled salmon that was absolutely delicious. Your photo got me salivating just looking at it and imagining the taste!

Bill

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 24 2015 13:51:09

keith

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From: Back in Boston

RE: Changes in sound of guitars over... (in reply to constructordeguitarras)

Ethan--I used accelerant in the context that some violin makers use ultra violet lamps to speed up the "aging" (oxidation) process--that is, to accelerate the process. Heat or another chemical is the catalyst? As to the first question, if wood is losing electrons the assumption is oxygen is gaining electrons and does the reduced oxygen have any affect on the components of the wood. I hope this question makes sense. I was curious about this and know you have a Ph.D in chemistry. Thanks.

REPORT THIS POST AS INAPPROPRIATE | Date Jul. 24 2015 13:59:35

constructordeguitarras

Posts: 1672
Joined: Jan. 29 2012
From: Seattle, Washington, USA

RE: Changes in sound of guitars over... (in reply to keith)

Keith--It could be that di-oxygen is converted to water in the process, which would evaporate. But reality is often more complicated....

I didn't know that about violin makers. Thanks for that bit of information. I wonder if they thought about the inside....

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REPORT THIS POST AS INAPPROPRIATE | Date Jul. 24 2015 14:50:36

Morante

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RE: Changes in sound of guitars over... (in reply to timoteo)

quote:

Here's how we do it in the Pacific Northwest. Cedar plank grilled salmon - starts out as tapas and ends up as a tapa. It's torrefied too!

As a one time professional fishing instructor and enthusiast eater of wild salmon and trout, this salmon seems seriously overcooked. Good for wood, maybe, but salmon should still be practically raw in the centre as it comes to the table. The centre cooks on the way. With a bottle of Chassagne Montrachet, of course.

REPORT THIS POST AS INAPPROPRIATE | Date Jul. 24 2015 15:10:17