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jandepora

How to close this kind of cracks

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I never see this kind of cracks where the crack don´t exceed the perimeter of the purfling. How could I do to repair this kind of cracks? I have to break the purfling to let the wood go its way, or maybe it could be done in other way.

thank you for your help.

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Might be possible to clean and pull that crack together, or it might require some removal of wood from the other edge and purfling, Can't tell from this side of the computer screen.

There's also the option of adding wood to fill the gaps, rather than removing original wood, but that's getting into some pretty tough stuff to do well. No shortage of hack jobs.

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As the cracks are now, the purfling will prevent them from closing.  Ideally, you can lift the purfling out of its groove to allow the cracks to close.  But if you can't do this, you might have to cut the purfling at the cracks.  You might also have to cut through the edges to allow the cracks to close.

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It’s not a simple repair, but the cracks can be repaired. I would do as much as possible to preserve the purfling. There looks to be a lot of dirt and/or varnish in the big crack, so I would focus on cleaning all of that out first. 

Once you have everything cleaned out you can reevaluate the cracks—the fit may be improved or the gap might be bigger. If it’s very close to fitting you may be able to moisten the wood gradually and persuade the crack to go back together. Otherwise, you might consider adding wood to the gap, as David Burgess suggested above.

I have seen some similar damage on several instruments. In my cases, it was caused by something pressing into the top in that area and cracking. I can’t say for sure that that’s what caused your violin’s damage, but it strikes me as a possible explanation. 

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3 minutes ago, The Violin Beautiful said:

If it’s very close to fitting you may be able to moisten the wood gradually and persuade the crack to go back together. Otherwise, you might consider adding wood to the gap, as David Burgess suggested above.

I'm curious how you would persuade the crack to close. If it was amenable to being closed it likely wouldn't be open. I think adding wood as David says is probably the way. Could cut very thin tapered strips of spruce and lay them firmly in the cracks, slightly proud to be leveled later. This might be a repair where cyano acrylate makes sense, so you could carefully position the pieces first and then apply glue. I guess the issue there is clean up though.

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Water carefully applied to the wood on the sides of the crack will swell the crack closer together. It’s a useful technique, especially on center seams that have come apart and sat long enough to deform.

Please don’t use CA glue on the violin! Hide glue is a very strong glue that will work wonderfully and it can easily be removed without harm to the top. Keep in mind that someone else will eventually work on the violin, and you don’t want to leave them a bigger problem than the one you found. 

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5 hours ago, bkwood said:

..............This might be a repair where cyano acrylate makes sense,..............

Nope.  Thorough cleaning, hide glue, tower cleats and shopmade bolt-through-plastic-pipe clamps.  If you want it flush, a cast should be used.  The bottom purfling is close to the saddle notch, can be teased out with the saddle removed, and the bitter end trimmed afterwards.  The top purfling is already buckled, so probably loose.  I'll defer to senior opinion here, but it looks to me like you could best cut it at a 45 degree angle, and after the crack is forced shut and level, trim the ends to form a scarf joint to fit the new width, glue it back, and touch up the varnish.

The one shown in the first photo is a puzzler, and I'm not sure of the best way to deal with the purfling there.

IMHO, CA glue shouldn't be used on any repair of this nature. :)

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Nobody has mentioned it before, but IMHO, this is definitely a top off repair. The cracks don't look new, and look to be filled with dirt. The first thing would be to remove the top, and clean the crack, inside and out, and then you can evaluate better what clamping or forming might be needed to close and glue the cracks. Retouching, after the work is done, will also be a challenge.

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14 minutes ago, FiddleDoug said:

Nobody has mentioned it before, but IMHO, this is definitely a top off repair.

Assuming he takes your advice, should he saw through the plate pin first ?

 

 

top pin.jpg

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The violin is the one talked in this forum.

I have repaired the back and know I am going with ribs, then I will glue all again and take the top off to repair the cracks.

I think I am going to clean the cracks one by one and see the better way for each one.

I thin I will do a sound post patch I. The top too.

 

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25 minutes ago, Delabo said:

Assuming he takes your advice, should he saw through the plate pin first ?

 

 

top pin.jpg

Sometimes I wet well first this part and take the top and let the pin in the block.

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These types of cracks are usually opening because the plate is deformed at some points, while the edge is still kept straight when it's glued to the ribs. First step would be to remove the belly from the ribs as suggested above and than care about the deformed areas. This was discussed several times before, either with careful dampening or in a plaster cast (or both).

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To echo Blank Face's observation, sometimes the cracks are caused by plate deformation due to bending. Removing the top, cleaning out the crack and letting the top relax can cause most of the crack to "close" naturally.

If the crack was caused by some stretching or shrinkage, then previous comments probably apply and you have a tougher repair.

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5 minutes ago, Blank face said:

These type of cracks are usually opening because the plate is deformed at some points, while the edge is still straight when it's glued to the ribs. First step would be to remove the belly from the ribs as suggested above and than care about the deformed areas. This was discussed several times before, either with careful dampening or in a plaster cast (or both).

I am always puzzled as to why you take a plaster cast of a deformed top ?

Would it not be better to un-glue and correctly realign everything before taking a cast ?

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14 minutes ago, Delabo said:

I am always puzzled as to why you take a plaster cast of a deformed top ?

Would it not be better to un-glue and correctly realign everything before taking a cast ?

Depends. The first step should always be the unglue and clean the old failed repairs or open cracks. Sometimes it's enough to work out deformations with the dampening method (using paper towels or the like), and/or with cleats. In case of multi-deformations, if you need to install a large patch resp. soundpost patch it's always better to do it in a cast to have a support for clamping and pressing out the deformations with sandsacks, either before or after glueing the cracks. One doesn't need to make a full cast everytime, often a partial cast can be enough, for example like it was described by Jacob here

 

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22 minutes ago, Delabo said:

why you take a plaster cast of a deformed top ?

To make it more clear, if this was what you are wondering about, the cast has to be corrected, scraped or filled, to the "right " form before pressing the plate into it. In case there are bigger deformations it can be necessary to make several times a new cast till you have reached the final state. Can be time consuming.

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I find it difficult to make reliable recommendations viewing damage from a 2 dimensional perspective... and I can't tell what, if any, portion of the top is severely deformed... or if a cast is required... but.. that said... it "appears" the cracks illustrated may be good candidates for lifting the purfling, relieving the edge, and closing the crack with a series of pillars, wedges and pillar clamps after the cracks are carefully cleaned. This technique can correct minor local deformations by allowing very effective control over the arching contour. I think you'll need to try and get the cracks as tight as possible. Adding small amounts of moisture near the crack at stubborn spots, if you have them, may help... but don't get things too wet or the wood can curl at the crack site.

It looks as though that in photo 1, the crack extends through the edge already (on the side of the summer grain closer to the saddle). If so, if edge material needs to be removed, that's probably where I'd do it. Didn't have time to blow up the other photos.

I don't know your level of experience, but if you go for lifting the purfling, it takes some care... try not to fracture it while you lift it or while it's free from the groove.  Don't stress it.  If it does come up for you cleanly, I believe you can redistribute it slightly around the bouts (once the cracks are closed) when you reglue it, and trim a little (where it will inevitably overhang) off the length at the saddle mortise to accommodate the lower bout cracks, and at the neck mortice to accommodate the upper bout crack.  If all goes well, no joint in the purfling will be necessary.

My 2 cents.

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4 hours ago, Delabo said:

I am always puzzled as to why you take a plaster cast of a deformed top ?

Would it not be better to un-glue and correctly realign everything before taking a cast ?

You would make a cast in order to have something to clamp against. The cast will have a negative of the deformation, but you can correct the cast and then use sandbags to gradually return the arch to its former shape.

It is possible to correct arches using other methods, but this one is the most widely used. 

Also, just to be clear, I am also of the opinion that this is a top-off repair, and one that will take considerable effort and patience to complete successfully. 

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If the purfling is "blocking" the crack it's an optical and technical much better way of repair to lift it (carefully dampening can help here, too) and cut it at a different place, just as Jeffrey explained.

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4 hours ago, Blank face said:

To make it more clear, if this was what you are wondering about, the cast has to be corrected, scraped or filled, to the "right " form before pressing the plate into it. In case there are bigger deformations it can be necessary to make several times a new cast till you have reached the final state. Can be time consuming.

One can also push and pull the arching around quite a bit, before making the cast, pushing it up in some areas, and pulling it down in others, using wedges or  screws.

I prefer this to making multiple casts, or doing extreme correction on casts, since most of us are better at seeing and discerning  a normal convex arching shape, than a negative.

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12 hours ago, David Burgess said:

I prefer this to making multiple casts, or doing extreme correction on casts, since most of us are better at seeing and discerning  a normal convex arching shape, than a negative.

The question was about casts, so I tried to shed some light on this. One could think of multiple ways to push an arsching, including to sit down on it with one's own.B)

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5 hours ago, Blank face said:

The question was about casts, so I tried to shed some light on this. One could think of multiple ways to push an arsching, including to sit down on it with one's own.B)

One thing about arching correction is that it takes a lot of time (weeks to months) of holding the plate in the correct configuration to get it to hold that shape. The casts, multiple or not, are a good, stable way to hold a shape.

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2 hours ago, FiddleDoug said:

One thing about arching correction is that it takes a lot of time (weeks to months) of holding the plate in the correct configuration to get it to hold that shape. The casts, multiple or not, are a good, stable way to hold a shape.

Right. What I was suggesting was tweaking the plate into shape as much as possible before making the cast, even though this may only be temporary. Then the cast can be used to hold it in place over a longer time span to get it to retain that shape. This can save a great deal of time and work making corrections to the cast, or making multiple casts.

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Seeing the cracks (1st and 3rd pictures) it looks like a problem with the musician chin pressure. The 2 cracks are around the place where the wood is worn.

I think it is why the cracks border the purfling and don't overpass the purfling.

Maybe it could be corrected with a local cast only...

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Probably you won't need a cast with this violin, it was more a theoretical consideration. Maybe the cracks will get closer after taking off the belly or dampening deformed areas, possibly taking away a bit wood at the edges as described. Then applying cleats might be enough.

Only if a soundpost patch is necessary, it would be better to do this in a cast.

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