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Top damage from bridge


D.Fenestrate
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I have noticed on many old fiddles that the top is literally eaten away in the area that the bridge sets on. I wonder why this is. It doesnt seem like just haveing the feet sit on the top would cause this damage. At some time have the bridge feet been glued down? Was this a common practice at some time in the past? In addition, would putting a drop of superglue on these areas damage the tone quality of the instrument? Any additional comments welcome. Thanks, DF

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My calculations show that a perfectly fit bridge foot will have a pressure of about half of the crush strength of the wood (perpendicular to the grain). However, at some time, it is inevitable that the foot will be tilted just a bit, and that would cause the pressure to exceed the strenght of the wood locally, resulting in small dents. The structure of the wood is destroyed in these areas, and over time these fibers will flake out. There could also be some creep/fatigue processes invovled. Glue is not the cause, and can not help.

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And add to Don Noon's explanation that the wood fibers of the top can be crushed by someone whacking the bridge or cramming the case full of stuff causing the case lid to press down on the bridge.

I wonder if anyone impregnates that are with glue or some other material when making a new violin. Certainly the old makers would have been aware of the problem. Somebody in the past would have tried strengthening this area along with the area contacting the soundost.

Any ideas on tonal results of doing this?

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Even if fitted perfectly, bridges tilt, and feet displace and often stick to varnish. That's just the way things are, unless you have a carbon fiber instrument.

I do agree that glue on the varnish probably isn't going to solve your bridge mark woes. But, if someone has tried it with success I'd be interested to hear how well the bridge came off later. :) I know petroleum jelly is supposedly good for protecting newly varnished instruments (or at least preventing excessive sticking) underneath chinrests.

I hadn't considered the closing force from a suspension or padded case lid (down on the bridge) as the source of wear - seems like a reasonable cause. I've also seen excessive plate distortion underneath a bridge when the plate is too thin, or the bridge/bar/post are off their marks.

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"I do agree that glue on the varnish probably isn't going to solve your bridge mark woes. But, if someone has tried it with success I'd be interested to hear how well the bridge came off later. "

Well, the areas I observe certainly have no varnish on them, they are little craters in the surface and I was just thinking of levelling off the crater with cyanoacrylate which when hardened will not stick to anything.

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"I do agree that glue on the varnish probably isn't going to solve your bridge mark woes. But, if someone has tried it with success I'd be interested to hear how well the bridge came off later. "

Well, the areas I observe certainly have no varnish on them, they are little craters in the surface and I was just thinking of levelling off the crater with cyanoacrylate which when hardened will not stick to anything.

Hi,

Where the bridge sits (or stands) there is a constant transfer or vibration and movement. Try to touch a vibrating string!. The problem is worse if the bridge foot does not sit well on the bass bar.

It may be the transfer of vibration that damge the wood fibres over a long time.

Wolfjk

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Less string pressure is great, but bare wood pressing onto varnish is still bare wood pressing onto varnish. I guess it depends on the Baroque finish?

Don - people insert maple into tops?

So until we can see the damage, no one here can make any strong recommendations. Do you have pictures?

Pouring resin into a void to level wear seems like an aesthetic fix only. Bridge wear is going to happen, it is common, and people often try to fake it. Most ugly wear is found on cheap old imports, rentals/abused instruments.

The violin top isn't an ebony frog (hard wood, could be filled with resin), it's light spruce. It vibrates (as stated above) and is under a lot of pressure. I would guess that any filler (other than a like material) would act as a blunted wedge, pressing hard into the spruce (depending on the extent of the wear). My guess - not reversible, and more harm than good?

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I hear what you guys are saying..... I guess my mind made the jump when I remembered that in several places I have seen descriptions of salvaging a string-cut bridge by using superglue, possibly mixed with some sawdust.

Less string pressure is great, but bare wood pressing onto varnish is still bare wood pressing onto varnish. I guess it depends on the Baroque finish?

Don - people insert maple into tops?

So until we can see the damage, no one here can make any strong recommendations. Do you have pictures?

Pouring resin into a void to level wear seems like an aesthetic fix only. Bridge wear is going to happen, it is common, and people often try to fake it. Most ugly wear is found on cheap old imports, rentals/abused instruments.

The violin top isn't an ebony frog (hard wood, could be filled with resin), it's light spruce. It vibrates (as stated above) and is under a lot of pressure. I would guess that any filler (other than a like material) would act as a blunted wedge, pressing hard into the spruce (depending on the extent of the wear). My guess - not reversible, and more harm than good?

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I've also noticed this can happen on new instruments as well, particularly when varnished too quickly (or the varnish is too soft). On some of the older ones the marks aren't where the bridge is supposed to be, or there are several marks where it's been moved, or only a part of the varnish has stuck to the bridge foot. I've even had a few where the varnish had sealed the bridge to the top...

Just Keeps Life Interesting.

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Re: Schleske pads/shims/veneers....

Does anyone know what wood...is it maple or something else?....also does he inset the shim or just glue to the top of the table?.............just curious :)

I was told by Joe that his are/were maple died black.Martin got the idea from Joe, and follows suit, I think. Absolutely neither Joe or Martin inset the pads. They are glued on to the top. Both sides are hide glue sized, then ca glue in between.

there is another innovation used by Martin on that top, anybody else notice?

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Thats interesting....Thanks Darren

Makes me thing of a contributor on another site who did the same/similar thing with a local australian wood. He was very pleased with the sound.

Also brings to mind another thread on another site ('soft shoe shuffle') where a contributor attatched mahogany veneers to the bridge feet and liked the tonal change....

Interesting stuff....must try it sometime...

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I was told by Joe that his are/were maple died black.Martin got the idea from Joe, and follows suit, I think. Absolutely neither Joe or Martin inset the pads. They are glued on to the top. Both sides are hide glue sized, then ca glue in between.

there is another innovation used by Martin on that top, anybody else notice?

...........................................................

I hope everyone will be doing this soon. I will not be doing it.

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