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violins88

Norway Spruce -- wood properties and map of Romania

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A friend is a professor of wood technology at North Carolina State University. He pointed me to this article.  More than you ever wanted to know about measuring acoustic properties of spruce, but the map of the Romanian Gurghiu Mountains is something I had not seen before. Many articles on wood technology are here. North Carolina made a decision years ago to find out how to maker paper from pine trees. This resulted in a top notch university department on the subject. They train the engineers who turn pine trees into paper. Their website is here.

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A friend is a professor of wood technology at North Carolina State University. He pointed me to this article.  More than you ever wanted to know about measuring acoustic properties of spruce, but the map of the Romanian Gurghiu Mountains is something I had not seen before. Many articles on wood technology are here. North Carolina made a decision years ago to find out how to maker paper from pine trees. This resulted in a top notch university department on the subject. They train the engineers who turn pine trees into paper. Their website is here.

Hi violins88,

 

Thanks for posting the article. I haven't read the whole thing but on page 6 they make the same mistake everyone does in declaring that the sapwood is not good tonewood. Yet it is found in almost every Guarneri 'del Gesù' in existence as well as Stradivari and many other Cremonese makers who evidently, according to the wood technologists, didn't know what they were doing.

 

You might want to talk to your friend and get them to revise the paper.

 

Bruce

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Hi violins88,

 

Thanks for posting the article. I haven't read the whole thing but on page 6 they make the same mistake everyone does in declaring that the sapwood is not good tonewood. Yet it is found in almost every Guarneri 'del Gesù' in existence as well as Stradivari and many other Cremonese makers who evidently, according to the wood technologists, didn't know what they were doing.

 

You might want to talk to your friend and get them to revise the paper.

 

Bruce

Bruce,

 

Thanks for that. I certainly will pass that along to my friend.

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Hi violins88,

You might want to talk to your friend and get them to revise the paper.

 

Bruce

 

 

Bruce,

 

Thanks for that. I certainly will pass that along to my friend.

 

The authors are from Romania and not NC State University. 

 

The address is "Sirul Beethoven 1" - how can they be faulted.

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The authors are from Romania and not NC State University. 

 

The address is "Sirul Beethoven 1" - how can they be faulted.

Hi Janito,

 

I thought it might be better if another specialist in wood technology (the one from NC State) got in touch with the specialists in Romania.

 

They state it was peer reviewed but this goes against actual observation of instruments from the old Cremonese school.

 

A violin-maker might not be recognised as a qualified revisor for peer review in this case.

 

Bruce

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They state it was peer reviewed but this goes against actual observation of instruments from the old Cremonese school.

 

A violin-maker might not be recognised as a qualified revisor for peer review in this case.

 

Bruce

I agree.

 

This one has flown the coup and unlikely that that particular journal solicits "Letters to the Editor" for feedback.  Something for the wood experts to note for the future.

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Hi Janito,

 

I thought it might be better if another specialist in wood technology (the one from NC State) got in touch with the specialists in Romania.

 

They state it was peer reviewed but this goes against actual observation of instruments from the old Cremonese school.

 

A violin-maker might not be recognised as a qualified revisor for peer review in this case.

 

Bruce

 

I agree.

 

This one has flown the coup and unlikely that that particular journal solicits "Letters to the Editor" for feedback.  Something for the wood experts to note for the future.

You won't know until you try.  My advice would be to take a multiply both-and approach.  Have both Violins88's friend and some musical acoustician with the requisite letters after their name as well as publication scalps hanging from their belt write a short "letter" article (citing the Dinicula et al article in question) containing the information on historical use of spruce sapwood, send a copy to the researchers, and submit it to the journal as well.  Just sayin'  :) .

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My major complaint about the paper is that the focus is almost entirely on the visual properties (ring width and late wood percentage), and doesn't really do a good job connecting that to the real physical/acoustic properties of the wood (speed of sound, density, damping).  There are plenty ...or even too many... of references to nebulous properties of sound conduction, intensity, stifled sound, radiation value, and other undefined characteristics.

 

It was interesting to see that the "better" resonance wood spec. calls for the lowest percentage of late growth... i.e. the dense part of the annual ring.  That is something I have found to be connected with density and speed of sound in the few samples I have tested.  Still, it would have been really nice to see some quantitative verification or correlation.

 

I wonder how much of this research is practical for a lumberjack trying to make a living.

 

Yeah, it does look like this paper is best suited for someone cutting trees who wants to sell the wood to Gliga.  If you're a violinmaker and want to find out what's the best acoustically, I don't think this is it.

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Is the lighter sapwood more flexible ?

Good question Ben.

 

I wasn't so much going into what might be the possible differences between sapwood and heartwood. Some other professors of wood technology here in Italy have told me there is hardly any structural difference in spruce. I was heavily leaning on the fact that sapwood is there and can be seen. This was further verified when dendrochronology demonstrated that Guarneri 'del Gesù' was using wood that was sometimes only a few years old in relation to the label date. Sapwood is, on the average, the outermost 20 to 60 rings into the tree from the cambium layer and the bark. The dendro dates were showing that the number of rings removed by 'del Gesù' was very small as the dating was very close to the construction date on the label. For the Lord Wilton the difference is only 3 years between the date on the label and the youngest dateable ring!

 

Bruce

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Thanks Bruce.  
It might be interesting to see an inventory of all the 'best' sounding violins 
(ie the ones the top players used over the last 100 years not the ones in banks)
and see how many of those have the stripey sap wood at the centre joint. 
I think it is more flexible actually, when you flex the plate diagonally in your hands. 

Also, when using UVA for weeks the spruce may go a lovely colour but doesn't it 
dry the wood and make it brittle ? That's something that Del Gesu didn't do for sure,
but wouldn't the wood he used 300 years ago have become similarly brittle with time ? 
 
 

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I wonder how much of this research is practical for a lumberjack trying to make a living.

Mike,

It's only useful to the lumberjack indirectly. Find how to process pine trees into something useful.

Incidentally, I recently observed logging operation close-up. Those machines are awesome.

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Hi Janito,

 

I thought it might be better if another specialist in wood technology (the one from NC State) got in touch with the specialists in Romania.

 

They state it was peer reviewed but this goes against actual observation of instruments from the old Cremonese school.

 

A violin-maker might not be recognised as a qualified revisor for peer review in this case.

 

Bruce

Hi Janito,

 

I thought it might be better if another specialist in wood technology (the one from NC State) got in touch with the specialists in Romania.

 

They state it was peer reviewed but this goes against actual observation of instruments from the old Cremonese school.

 

A violin-maker might not be recognised as a qualified revisor for peer review in this case.

 

Bruce

My friend has passed this link to the author in Romania.

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Is the lighter sapwood more flexible ?

Hi Ben,

The quality of the sapwood depends on when the tree is cut down. If it is harvested in the growing season it is likely to contain more sap and more resin. It is also more prone to fungus and insect attacks.

If the reeding is full of sap and resin, even after it dries it will be less resonant.

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Good question Ben.

 

I wasn't so much going into what might be the possible differences between sapwood and heartwood. Some other professors of wood technology here in Italy have told me there is hardly any structural difference in spruce. I was heavily leaning on the fact that sapwood is there and can be seen. This was further verified when dendrochronology demonstrated that Guarneri 'del Gesù' was using wood that was sometimes only a few years old in relation to the label date. Sapwood is, on the average, the outermost 20 to 60 rings into the tree from the cambium layer and the bark. The dendro dates were showing that the number of rings removed by 'del Gesù' was very small as the dating was very close to the construction date on the label. For the Lord Wilton the difference is only 3 years between the date on the label and the youngest dateable ring!

 

Bruce

I just wanted to bring up that the definition of sap wood and heartwood (also called the pith) varies depending on the source.  From my plant physiology books, anything interior of the cambium layer is heartwood and the cambium and exterior wood is sap wood.  Others define any living wood (wood that still transports water and nutrients) as sap wood with only the central dead area as heartwood.  The 20 - 60 rings from the cambium layer may be from the second definition.  Possibly it is from another criteria that I'm not familiar with.  I've not read the paper yet, but understanding the authors definition of a term can sometimes change ones understanding of the authors conclusion.

 

-Jim

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Hi Ben,

The quality of the sapwood depends on when the tree is cut down. If it is harvested in the growing season it is likely to contain more sap and more resin. It is also more prone to fungus and insect attacks.

 

There's pretty good agreement on that from the "lore" people, but results from actual testing show sap and resin being about the same year-round, or maybe even trending toward higher in fall and winter, energy stored for the spring growth spurt.

 

Fungus and insect attacks probably have more to do with temperature, and water content of the wood, than anything else. Sure, If you cut down wood in summer, it's more likely to mold, due to the higher temperature. You might notice that mold growth is inhibited by putting food in the refrigerator, and largely eliminated by putting it in the freezer.

 

You might also notice that dried food products, with very low water content, are highly resistant to mold. Compare the shelf life of dried rice, with the shelf life of rice which has been hydrated for eating.

 

So if you cut wood in the winter, giving it a little time to dry before temperatures get warm enough to be friendly to mold growth, you might be better off. But so far, I haven't found any good  evidence relating it to seasonal sap content. And we all know that even super-high sugar content granulated dry sugar, doesn't suffer from mold growth.

 

Next, maybe can argue about which phase of the moon is best for harvesting, and how advantageous it is to be wearing ones "lucky socks". :lol:

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Is the lighter sapwood more flexible ?

 

Presumably by "lighter" you mean lower density, and asking if it is less stiff.

If so, yes... there is an extremely strong correlation between density and stiffness.

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Presumably by "lighter" you mean lower density, and asking if it is less stiff.

If so, yes... there is an extremely strong correlation between density and stiffness.

Is there an optimum range of densities you like?

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Is there an optimum range of densities you like?

 

I kinda am leaning towards .36 - .4 as a nice range, which seems to be where the really good old fiddles seem to fall.  Perhaps even higher density would work well, but I haven't done much with really good, higher density wood.  Of course, density is only part of the picture, as modulus (stiffness) can vary quite widely even for the same density.

 

That is for violins, where I think the size/shape of a normal size violin and the expected performance/tone is somewhat restrictive of what wood properties will work.

 

For violas and larger instruments, I think it is more accommodating of lower densities.

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One other thing seems odd to me about the paper...

 

In figure 2, it shows that the rings are wide, and latewood percentage is high (both bad) in the heartwood.  Then as the sapwood begins, ring spacing becomes closer,and latewood percentage drops (both good).  Then, towards the outer rings of the tree, the spacing becomes wider and latewood fattens up again.  This bring up the question:  what would they have found if they cut that tree 50 years ago, before the "bad stuff" on the outside got created?  Or do the rings and latewood shrink over time as new rings grow outside of them (seems unlikely).  This just seems odd.

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Hi Ben,

The quality of the sapwood depends on when the tree is cut down. If it is harvested in the growing season it is likely to contain more sap and more resin. It is also more prone to fungus and insect attacks.

If the reeding is full of sap and resin, even after it dries it will be less resonant.

Hi Wolfjk,

 

I didn't want to get into the harvesting question so much as I wanted to point out that sapwood is frequently to be found and observed in fine instruments. The old tale that the sapwood (by this I mean alburnum) has to be cut away because it is acoustically inferior is totally unfounded for spruce wood.

 

As I understand it, in their transformation into heartwood (by this I mean duramen) the former sapwood cells thicken and the small tube endings close off as they are no longer needed for containment or transport of nutrients but serve as structural support for the tree.

 

Bruce

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