vathek

Curious about this grain pattern in spruce violin top

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2 hours ago, vathek said:

I personally have not seen a pattern like this before and wonder if it has a name and what causes it.

Sandpaper finish and a probable water stain. 

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The waves are in the wood, and under the varnish. It has never been sanded but I did have it polished at Shar as the the chippy varnish had lighter spots and the polish gives it a more uniform look

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1 hour ago, Bruce Carlson said:

Sandpaper finish and a probable water stain. 

 

46 minutes ago, vathek said:

The waves are in the wood, and under the varnish. It has never been sanded but I did have it polished at Shar as the the chippy varnish had lighter spots and the polish gives it a more uniform look

I agree with Bruce, sandpaper finish or some other sort of abrasive finish on the bare wood, not on the varnish.

Sometimes even an energetic rubbing with paper or cotton rags could destroy the straight pattern of the medullary rays on the spruce, it is a very delicate wood.

When you say that it has never been sanded, are you referring to the varnish or wood?

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I agree with Bruce and Davide. You get that pattern on spruce when you sand with grit finer than 150 or so. Rubbing the bare spruce with a cloth will produce this too. If you scrape, you do not get this medullary ray pattern. 

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It definitely looks like rays that are stained somehow.  I don't have the sanding experience to say for sure, but it seems that sanding along the grain would be sanding perpendicular to the rays, and could tear them up so that they hold or absorb stain preferentially.  Whether you sand or scrape, the ray pattern will always be there... but it could make a huge difference in how it shows up.

I was also thinking that the photos seemed to be patchy, like some areas of the varnish wore down (or were sanded down) to bare wood and then touched up at some time in the past.

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I agree 100% that is an "artifact" of sanding a raw wood curved surface with vertical grain , particularly with very fine grits.  If after this sanding procedure was done, a fine scraper was used over the sanding, a large portion of this visual effect will disappear. 

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9 hours ago, Bill Yacey said:

Why would you think this Bruce? The waves appear in the wood, not a surface texture.

Hi Bill,

Yes, it IS in the wood. It is the medullary rays on a curved surface as Jezzupe and the others said. They are enhanced by sanding. If an arching is properly finished (usually with a scraper or careful minimal sanding paralell to the annual rings) this effect is minimized. The rays, obviously, are going to be most visible on the quarter cut.

Bruce

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Sorry, I misunderstood your  earlier post. I was reading that the scratches in the wood surface is what was pictured.

  I've seen these sorts of markings on some Engelmann wood I've used in the past, although it was strictly scraped; no sandpaper involved.

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1 hour ago, lpr5184 said:

Is there something wrong with the way this looks? I think it looks fine. There is no blotching. What am I not seeing?

In photos 1, 3, and 4, there are patch-like areas where the rays are redder and more pronounced, even though the ray pattern itself isn't much different from surrounding areas.

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2 hours ago, lpr5184 said:

Is there something wrong with the way this looks? I think it looks fine. There is no blotching. What am I not seeing?

Whether you like it or not is a matter of taste but it does tell us something about how the spruce top was finished. It is rarer than hen's teeth to find this on an unadulterated spruce top from the Classic Cremonese school and from many of the better makers after and elsewhere. I am from the group who avoids creating this feature at all costs (again, a matter of taste).

Bruce

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1 hour ago, lpr5184 said:

OK, I think I see it now...It could look like blotching if the rays are concentrated in areas.

That's not my point... I mean that the ray concentration isn't all that different, but there are some areas where the rays are a different (and more intense) color, and even the whole area appears to be a slightly different color.  To me, that might indicate a touch-up that went down to the wood.  Or maybe some funny lighting effect in the photos.

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1 hour ago, Jim Bress said:

rare chicken

If you suppressed the wing gene too and got the little clawed arms, it'd be even more impressive.   I've always wanted to do that and give one of my old paleo profs a real surprise for Christmas.  Where's that DNA guy who used to post here?  :lol:

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1 hour ago, Violadamore said:

If you suppressed the wing gene too and got the little clawed arms, it'd be even more impressive.   I've always wanted to do that and give one of my old paleo profs a real surprise for Christmas.  Where's that DNA guy who used to post here?  :lol:

Geez VDA, you're familiar with Harris' work too?!  I'm going to change your name to Spock, or Hal, or Skynet. :D

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to explain this some more in order to aid understanding of what we are seeing,,,,we will refer to this as an "artifact" ie. something left behind from a process that gives one clues as to what that process was.

First I would say what is more "proper"for violins or what would be more expected and perhaps more desired,particularly if being judged, if I'm not mistaken would be a scraped finish on the raw wood, This will make it so the "reeding" or corduroy grain pattern will be more pronunced and this underlying "cross grain dog fur medulary ray effect"  while still there as it is inherent, it will not stand out or be seen nearly as much if the raw wood surface was prepared using fine grit paper, the finer the grit the more this will stand out.

even though vertical grain woods by in large demonstrate a "vertical grain" look within the entity of the cut,  the cross grain flinches that exist in the cut related to its thickness, reside in wood  as if in layers of flitches, like layers of plywood may be a good way to visualize it...

So as the arch falls from the top to the edge , if the spruce were in fact ply wood we would see the different layers exposed as we get deeper and deeper into the wood., this can be seen in certain knife handles that use laminated colored ply layers. So what you are seeing a similar effect that is not showing as layers of plywoodfalling away form the top peak of the arch, but because it is solid wood, we see the flitches jump out when polished,making them shine, or stand out when varnish hits them, and then as these are telegraphed through the varnish falling away from the top peak of the arch to the edge,this pattern is left behind, jumping out in certain light and disappearing in others, like "mini chatanoyance"...

As this visual artifact pretty much only presents itself when fine sandpaper is used, it is a "tell' as pointed out by Bruce of how the instrument was created.

In guitars, as it is "ok" and common to sand for final surface prep, this visual artifact is somewhat desired and or expected. owever because most guitars are not arched, the effect  does not show so much as it would if it is an arched top, the "falling away" layers thing does not show  as dramatically as see in these pics, but the flitch effect will be seen

 

 

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