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polkat

Fix this crack?

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The picture shows the upper treble bout of the top plate. I had to shoot a lot of angles just to get the crack to show.

This is on an old copy I restored for my own use. The crack wasn't visable (maybe not there) when I glued the plate back on maybe 3 months ago, and the purfling is not cracked. I'm guessing the clamps cracked it while gluing and I just didn't see it. To make sure it won't spread, I'd like to try wicking some glue into it without removing the plate again if possible. It will just barely appear open a tiny amount if I put pressure on the outer edge, but I may be seeing things.

Can I effect a repair on this without cleating?

Thanks!

post-5120-1276499007_thumb.png

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its not the cleating thats the issue, ive talked to a top maker who says he sometimes forgoes cleats on really strong crack repairs, the issue is your wicking glue in is going to only cover roughly half of the cracked surfaces, the rest is going to be too tight together to let the glue in, from a utilitarian standpoint if the crack is not buzzing before or after youre repair i guess youre ok but how do you explain a crack that visible to the customer, you can't claim its properly repaired because it isn't. you can say and i have done this, this hairline crack is temporarily repaired but next time the top has to come off for repairs it should be taken care of but for now it is not buzzing or affecting the tone, thats my opinion, sincerely lyndon :) :) :)

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Thanks lyndon! It doesn't buzz or effect the tone as is. I am the customer (it's one of my personal players), and for my own stuff I'm a bit less critical about this kind of thing. I don't care if the crack on this lower level instrument shows, as long as I can get enough glue in to keep the crack stable. In fact, I just studied the underside with my mirrors and can see no evidence that the crack goes all the way through (usually you can see them on the underside simply by pushing on the top of the crack), so maybe I'll get lucky until I can fix it proper.

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id use a pretty dilute hide glue so it soaks in more and comes apart easier when you have the top off to fix it proper, good luck, sincerely lyndon :)

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Thanks lyndon! It doesn't buzz or effect the tone as is. I am the customer (it's one of my personal players), and for my own stuff I'm a bit less critical about this kind of thing. I don't care if the crack on this lower level instrument shows, as long as I can get enough glue in to keep the crack stable. In fact, I just studied the underside with my mirrors and can see no evidence that the crack goes all the way through (usually you can see them on the underside simply by pushing on the top of the crack), so maybe I'll get lucky until I can fix it proper.

++++++++++

Putting glue on top of a crack is not a repair. It is a cover of a crack.

Whether you see the other lower half of the crack or not, it must be be there.

Why a crack is only on the top half ? I would open the edge glue line and make sure

the lining level and re-glue everything. If the lining is level, the top half when it is glued

would be invisible. I think the surface of the lineing near the neck is low now. Just my guess.

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i must admit i dont try gluing violins with the top on, i would just leave the crack if it is not buzzing it will be easier to fix when you have the top off, fellows right its not really 'fixing' is it, sincerely lyndon

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To make sure it won't spread, I'd like to try wicking some glue into it without removing the plate again if possible. It will just barely appear open a tiny amount if I put pressure on the outer edge, but I may be seeing things.

I often glue cracks from the outside. In order to "wick" glue into the crack you have to flex the crack, and it is hard to flex a small crack like this. To make it easier to flex the crack, I would separate the top/rib seam from the crack to a little past the corner. Then reglue the seam after the glue in the crack has dried. Some people on this forum have recommended using a small rubber suction cup to pump glue into the crack, but I've never tried it.

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It looks like something struck the side... pretty big edge dent. It's always important to flex plates before reinstalling them.

Do people really "wick" glue? I generally always flex the plate like you Brad.

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i generally always take off the top and fix it proper, if you have a fresh crack that has never been glued you have the opportunity to fix it properly with the top off and make it virtually dissapear, you lose that opportunity if you do a cheapie quickie fix from the outside, you dont get the surfaces clamped together as well, you dont cover the whole crack and later when you have the top off and try to fix it properly, you may have trouble getting it apart then you have to get rid of all the old glue and by the time you finally get it glued you have an uglier crack line not to mention a weaker join, theres a reason why they reccomend taking your violin to an expert, because the experts dont take shortcuts and do things right adding to the value of the violin not reducing it in value, sincerely lyndon :)

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Do people really "wick" glue? I generally always flex the plate like you Brad.

I assumed that by "wicking" polkat meant flexing the crack to draw glue into it.

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wicking... verb... to draw off (liquid) by capillary action

It's not really capillary action drawing the glue into a joint... just surface tension?

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wicking... verb... to draw off (liquid) by capillary action

It's not really capillary action drawing the glue into a joint... just surface tension?

I don't think it's surface tension. Surface tension tends to hold liquid together as you see when you put a single drop of water on a sheet of glass. So I think surface tension would tend to prevent glue from running into a crack, and it will only run in by overcoming its surface tension.

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Yes, I meant what Brad said. Did it last night with thin glue. I did open the plate from the neck to a few inches past the crack, and found a tiny piece of grit that I must have missed before, directly under the crack, so I think that my thought that the original clamping must have induced the crack was correct. Also, with the crack loose, it would still only barely flex open at the top and could not be gently seperated at all, so I still think the crack was forced apart at the top and not completely through. Anyway, here's how it looks now, and since it's just a throw in the car and take to the campground, it's fine with me....

post-5120-1276542743_thumb.png

post-5120-1276542801_thumb.png

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I did open the plate from the neck to a few inches past the crack....

I would have opened it a bit past the corner to be able to flex the crack better.

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If you were able to get a little flex, you're probably fine.

It looks like wicking is a fine term. I'm so used to thinking about fluid soaking through a porous material when I hear "wicking", rather than traveling through/between something

capillary action, capillarity, capillary motion, or wicking refers to two phenomena:

1. The movement of liquids in thin tubes.

2. The flow of liquids through porous media, such as the flow of water through soil

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