vathek

Curious about this grain pattern in spruce violin top

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Thank you Jezzupe for the explanation. As mentioned in original post, the varnish had chipped in some places and when I had it polished apparently some of the polish soaked in to the unprotected places. For myself, I actually really like the effect, and think it adds interest to the top. If I were to ever commission a violin I'd probably request that effect. Enclosed is another pic to give a more accurate view of what the whole top looks like.

vlngrain1.jpg

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1 hour ago, vathek said:

Thank you Jezzupe for the explanation. As mentioned in original post, the varnish had chipped in some places and when I had it polished apparently some of the polish soaked in to the unprotected places. For myself, I actually really like the effect, and think it adds interest to the top. If I were to ever commission a violin I'd probably request that effect. Enclosed is another pic to give a more accurate view of what the whole top looks like.

If you wish to use sandpaper I have noticed that if you sand in a line parallel to the annual rings the swirl effect is eliminated or minimized. Sanding this way breaks up the medullary rays into small pieces that are at right angles to the annual rings and only of the width between two adjacent rings.

You will obtain more of this effect if you sand in different directions and as Mike Molnar said earlier, using finer grit sandpaper.

If I was judging in a violinmaking competition I would give lower marks for wood finish. Sandpaper, if not used judiciously, can ruin an otherwise well carved instrument. If it's your violin you are making you can do whatever you like, no problem, to each his own.

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By coincidence I was admiring some photos of a G. Fiorini violin this afternoon that seemed to have this feature on the bass side of the top (photo edited by me just to show the upper bout).    I had thought it was an indication of a really good wood choice.  I had always thought that the presence of distinct "bear claws" said something of the density of the wood.  So that thinking is all wrong, right? 

Fiorini_Final-.jpg

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I pay high attention to anything Bruce has to say, from both having worked in close proximity to him in the Weisshaar shop, and later having judged alongside him. His powers of observation and analysis are pretty amazing, among the best.

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3 minutes ago, David Burgess said:

I pay high attention to anything Bruce has to say, from both having worked in close proximity to him in the Weisshaar shop, and later having judged alongside him.

I feel the same way and I've never met him. The man is highly credible.

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16 minutes ago, vathek said:

I remember a recent thread re: bearclaws, are they produced the same way?

No, bearclaw is a feature sometimes present in certain species of spruce; especially Picea abies better known as Norway spruce in Europe. The cambium layer under the bark, where the new wood cells are generated towards the center of the tree and the new bark towards the outside, has a distict appearance as if a bear had pulled it's claws down the trunk. Each one of these "scratches or grooves" generates over time a wavy pattern in the annual rings which are revealed when the plate is sawn out for violinmaking.

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17 minutes ago, vathek said:

I remember a recent thread re: bearclaws, are they produced the same way?

Nope.  We are talking about rays here.  Bearclaw is a squiggle in the grain.  Completely different.

Bruce beat me by a few seconds.

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It would be great if someone would post a side by side photo showing what the differences look like up close. Bruce takes awesome photo's....:)

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12 hours ago, Bruce Carlson said:

If you wish to use sandpaper I have noticed that if you sand in a line parallel to the annual rings the swirl effect is eliminated or minimized. Sanding this way breaks up the medullary rays into small pieces that are at right angles to the annual rings and only of the width between two adjacent rings.

You will obtain more of this effect if you sand in different directions and as Mike Molnar said earlier, using finer grit sandpaper.

If I was judging in a violinmaking competition I would give lower marks for wood finish. Sandpaper, if not used judiciously, can ruin an otherwise well carved instrument. If it's your violin you are making you can do whatever you like, no problem, to each his own.

Why does finer grit sandpaper give more of the effect? Does a coarse grit damage the rays so much that they are camouflaged? I woke up in the middle of the night and started wondering about this :rolleyes:

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3 hours ago, Muswell said:

Why does finer grit sandpaper give more of the effect? Does a coarse grit damage the rays so much that they are camouflaged? I woke up in the middle of the night and started wondering about this :rolleyes:

Finer grit sandpaper leaves the harder radial rays and annual rings relatively undisturbed and eats away the softer spring growth. This leaves the radial rays and the annual rings more in evidence. The coarser grits destroy everything in their path and tend to break up the swirl pattern. But if you left the table finished only with a coarse grit, it probably would be great to look at.

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Can the same effect come from a sharp scraper that leaves a very smooth finish on the wood?  Do you have to use a dull scraper to eliminate this effect? 

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How evident are the annual rings in the white?  In other words, does the visual effect come up and bite you only after varnish is applied or can it be observed and mitigated (should it occur) during the final wood preparation?

Thanks,

Jim

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1 hour ago, MikeC said:

Can the same effect come from a sharp scraper that leaves a very smooth finish on the wood?  Do you have to use a dull scraper to eliminate this effect? 

Dull scraper?

 
I do not know what they are.....:)

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1 hour ago, Bruce Carlson said:

Finer grit sandpaper leaves the harder radial rays and annual rings relatively undisturbed and eats away the softer spring growth. This leaves the radial rays and the annual rings more in evidence. The coarser grits destroy everything in their path and tend to break up the swirl pattern. But if you left the table finished only with a coarse grit, it probably would be great to look at.

Thanks Bruce.

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1 hour ago, Jim Bress said:

How evident are the annual rings in the white?  In other words, does the visual effect come up and bite you only after varnish is applied or can it be observed and mitigated (should it occur) during the final wood preparation?

Thanks,

Jim

Here is a cross section of end grain together with the outermost wood of the trunk which would have been in contact with the cambium layer. You can see it in the trunk surface, like bear claw scratches and you can see the dents in the annual rings caused by the irregular surface of the cambium layer. It is possible to tell if a tree has bear claw or not before it is felled, just remove a bit of the bark.

5a2805e3cf29b_endgrainandbarkoff.thumb.jpg.30441e14c1227bf80087a185004e7d62.jpg

The second photograph is bear claw as you would see it on a flitch of spruce ready for making.

5a280781c88ba_bearclawonawedgeofspruce.thumb.jpg.e585fb09fd17c67712e877a1fddea8b7.jpg

Bear claw on a Landolfi violin

5a2807e487715_voLandolfibearclaw.thumb.jpg.c833445626813d2a1af07b1ab8874bfc.jpg

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That first photo is the best I've seen at showing the basis of bear claw.  Completely different from the flame of maple.

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3 hours ago, Davide Sora said:

Dull scraper?

 
I do not know what they are.....:)

I hear that Strad used broken bits of sword blade.    Do you have corduroy texture on the spruce top?   If so, how do you get that?    

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1 hour ago, MikeC said:

I hear that Strad used broken bits of sword blade.    Do you have corduroy texture on the spruce top?   If so, how do you get that?    

Not wanting to speak for the great Davide Sora, but my take is that a very razor sharp scraper used as the final pass "cuts" the wood and therefore does not fall into the softer grain as sand paper does, this reducing grain mottle or micro accentuation of grain features, the scraper sharpness makes it so the material acts more homogeneous.

Fine grit papers heat up very quickly, this "burnishes" the material also aiding in it jumping out more.

The angle that you hold the scraper also effects the final look, this is dependent on the burnish angle that you put on your scraper, I like it at a 90' angle, then tilt it some. The wood itself will also have a direction that "smooths/cuts" better one way or another, a nicer finish may be had going for the bottom to the top with the grain, or the other way around depending on the "dog fur with grain lay up" of the fibers

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Scrapers are very versatile tools depending on the type of sharpening, the way with which the cutting edge is turned that determines their aggressiveness, the pressure and the angle that is held during working and the cutting direction.

Also sandpaper can be used with more or less pressure and with different grit with different results.

What I have noticed is that with scrapers, the compression of wood is practically inevitable while with sandpaper can be reduced almost to zero, obtaining smoother and flat surfaces.
This is particularly noticeable after having wetted the wood raising the grain, which at this point is more marked with the scraper than with the sandpaper.
But I must admit that I have not explored all the possibilities with the latter very much, since I abandoned the use many years ago for the surface finishes and I never looked back because I hate to breathe its dust.;)

Regarding Stradivari's sword blade scrapers, we really don't know if they were the only ones he had, apart from the fact that those in the museum could most probably come from Ceruti.

I do not want to claim that my way to finish is equal to that of Stradivari, is only what I prefer for my instruments and that I think is closer to the appearance of the wood that I like on some ancient Cremonese instruments, but not all are the same and I even might be wrong, sometime.....:o:)


 

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From my experience, the effect of strong medullary rays in OP is sometimes called "silking" in guitar or mandolin world and typically folks like the appearance. Some spruces tend to have less of it (red spruce) some more and individual trees differ as well. If the wood has strong medullaries you will hardly get rid of it completely even if you use scrapers or rough sandpaper. Any stain (even light colored) will bring it out more (think of quartered oak) and rougher surface of the rays will take more color than polished smooth so the contrast between the rays and softer early wood will be more apparent on wood sanded to a very smooth surface.

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