Mat Roop Posted October 3, 2020 Report Share Posted October 3, 2020 So I have this sentimental VSO that arrived in my shop. The center seam on the top about between the bridge and fingerboard has released, but the gap appears less than paper thin. The violin is not worth almost any repair, but because of the sentimental value to the client, they'd like to have it playable. Top removal is really out of the question, and my usual tactic for this type of situation, is to the heat all surfaces well, have the glue a bit on the thin side and use a small suction cup to press the glue in, and flex as much as possible without making the separation run.. Thinking about this, for now and the future, is there a surfactant that can be added to hide glue to help it pull into the seam? will it affect holding power or future repairs? Appreciate any thoughts... Thanks, Mat Quote Link to comment Share on other sites More sharing options...
FiddleDoug Posted October 3, 2020 Report Share Posted October 3, 2020 I'd say no to surfactant. In this case, you're not sucking the glue into the joint, you're pushing. Making the glue a little on the thin side would probably help if it's a really narrow joint. Quote Link to comment Share on other sites More sharing options...
Evan Smith Posted October 3, 2020 Report Share Posted October 3, 2020 For this type of situation I would take a piece of spring steel, long and narrow,( .015,, or .010,, or several.005's together,, whatever you got laying around that feels right). Put clear packaging tape on one side so the glue can't stick or rust,, if any glue leaks through. Then hold them in place on the inside, centered along the seam with some magnets placed on the outside. Put in some sound posts along the seam, just tight enough to start to open the seam a bit, remove the magnets, then work in the glue, knock out the posts and clamp the arch from the outside with slight pressure. Did I mention Slight pressure? You will want to test the crack with the sound posts first without the metal liner in place,, and figure out your limits, and just how loose and far the crack actually is. They don't have to be pushed over the back seam to do the job. Slightly round both ends, they can be regular cheap dowels,,, put leather on the sliding end if you want,,,,etc. Run through it with the posts first and get them figured out. As soon as you put one in too tight the one beside it will drop... have some string on them for easy removal. It is definitely a delicate, "Watch Makers" type of operation. A bit of practice and you develop a "feel" for it. A dedicated narrow ruler with a vee ground in the end to catch the top of the post and keep it in place,, while you push the bottom of the post under to tighten it,, will make it much easier. Also put masking tape on the steel, on the post side,,, to give it some traction so it doesn't slip around. To clamp the outside, again a long thicker piece of spring type steel along the crack, (with clear tape for no stick) with bass bar sized blanks across the top side to side,, and use those cheap small plastic bar clamps. Clamp from the wooden cross bars to the edge of the back plate to pull the top toward the back plate and close up the crack. I have deliberately clamped several tops in this way to their breaking point (just for a test on junk) and it takes a lot more than you would imagine to break it. The first place they give out is a split from the upper eyes to the top edge, then the lower holes blow. Just be reasonable and all will go well. To close the crack the metal is not usually necessary, just a few cross bars judiciously clamped will do it. as you push down on the top the crack is automatically being pushed together, just don't make a flat spot. Check that out ahead of time, it is usually fine, but sometimes a curved caul might be in order, most likely not,,just depends. Did I mention,, Slight pressure? At first this may seem overwhelming but after you got it it is really useful for loose bass bars, cracks, center seams,, smashed, stepped upon, sat upon,, cheap fiddles, pull out the pieces prop them up and glue, I have been shocked how well things turn out, just another way of thinking about it. quck and dirty, but still a good solid job. Good enough is good enough for some things,,,just a few more miles, another year. and kid's 'done. Probably not so quick the first time,, I can make it look easy. Quote Link to comment Share on other sites More sharing options...
avandesande Posted October 3, 2020 Report Share Posted October 3, 2020 Does it go all the way through? Wouldn't stringing it up and tensioning it pull the crack together? Quote Link to comment Share on other sites More sharing options...
Mat Roop Posted October 3, 2020 Author Report Share Posted October 3, 2020 thanks Evan... good ideas. What I have done also is taking a 90 degree bent instrument screwdriver and with a pad on the end, thru the f hole and then levering the joint up to open the seam, lower to close and with the hot glue over the seam, this repetitive motion works the glue in. I'm still curious about the surfactant idea and sent an email to Milligan &Higgins to see what they have to say... cheers, Mat Quote Link to comment Share on other sites More sharing options...
Mat Roop Posted October 3, 2020 Author Report Share Posted October 3, 2020 1 hour ago, avandesande said: Does it go all the way through? Wouldn't stringing it up and tensioning it pull the crack together? yes, and yes... but it needs to be reglued otherwise the separation will continue until the top is in 2 halves.. then the whole top needs to come off. So the question in my mind really was how best to get the glue into the separation when you can't really pull it apart.... and the surfactant idea came to mind, but I don't know which surfactant to use ( if any) or the consequence of using it. Cheers, Mat Quote Link to comment Share on other sites More sharing options...
fiddlecollector Posted October 3, 2020 Report Share Posted October 3, 2020 Dont know about surfactant but alcohol is often used to wet or break surface tension before applying glue in other circumstances such as art restoration. Quote Link to comment Share on other sites More sharing options...
Brad Dorsey Posted October 4, 2020 Report Share Posted October 4, 2020 2 hours ago, Mat Roop said: ...a 90 degree bent instrument screwdriver and with a pad on the end... I'd like to see a picture of this if you have one. Quote Link to comment Share on other sites More sharing options...
donbarzino Posted October 4, 2020 Report Share Posted October 4, 2020 I was taught to soak some hot water into such a crack just before applying the hot glue so as to draw the glue down into the crack as the water soaks into the wood. Quote Link to comment Share on other sites More sharing options...
Mat Roop Posted October 4, 2020 Author Report Share Posted October 4, 2020 4 hours ago, fiddlecollector said: Dont know about surfactant but alcohol is often used to wet or break surface tension before applying glue in other circumstances such as art restoration. Alcohol is dangerous around violin varnish! Quote Link to comment Share on other sites More sharing options...
Mat Roop Posted October 4, 2020 Author Report Share Posted October 4, 2020 3 hours ago, Brad Dorsey said: I'd like to see a picture of this if you have one. Pretty simple.... a screwdriver bent 90 Degrees & covered with plastic tubing. Mostly used for F-hole cracks. .. Heat crack, Lay a bead of glue on crack, insert tool thru f hole and lift one side of crack from underside, then push down from outside.. pulsating up & down, and glue works in nicely. Problem with my current situation is that there is very little flex ( almost none) in the area to be glued. Evan's post above is helpful. Quote Link to comment Share on other sites More sharing options...
fiddlecollector Posted October 4, 2020 Report Share Posted October 4, 2020 7 hours ago, Mat Roop said: Alcohol is dangerous around violin varnish! Yes i know, but depends how careful you are ! Theres a pdf link to the article which is quite interesting. Ive repaired cracks where i just use a hyperdermic to put a little ethanol in the joint and then let dry around 5-10 minutes before adding glue to the joint. (this is an alternative to adding alcohol to the glue) Animal_glues_a_review_of_their_key_prope.pdf Quote Link to comment Share on other sites More sharing options...
Bodacious Cowboy Posted October 4, 2020 Report Share Posted October 4, 2020 I could imagine myself spending more time thinking about how to do this without taking the top off than it would to just take the top off... Quote Link to comment Share on other sites More sharing options...
Mat Roop Posted October 4, 2020 Author Report Share Posted October 4, 2020 3 hours ago, Bodacious Cowboy said: I could imagine myself spending more time thinking about how to do this without taking the top off than it would to just take the top off... For sure, but once you have it figured out... bob's your uncle! ...cheers, minimalist Mat 4 hours ago, fiddlecollector said: Yes i know, but depends how careful you are ! Theres a pdf link to the article ....Animal_glues_a_review_of_their_key_prope.pdf 176.57 kB · 0 downloads Thanks fiddle collector... great article, and helpful! ... Mat Quote Link to comment Share on other sites More sharing options...
Bill Yacey Posted October 4, 2020 Report Share Posted October 4, 2020 I wonder if taping up the F holes and applying a medium vacuum source momentarily to the endpin hole would draw the glue in from any cracks? Quote Link to comment Share on other sites More sharing options...
David Burgess Posted October 4, 2020 Report Share Posted October 4, 2020 39 minutes ago, Bill Yacey said: I wonder if taping up the F holes and applying a medium vacuum source momentarily to the endpin hole would draw the glue in from any cracks? Interesting idea. My first try might be applying mild air pressure (less air pressure than would blow the tape off the ff-holes) to open the crack enough to facilitate getting the glue in, and then applying vacuum to clamp it. Quote Link to comment Share on other sites More sharing options...
Mat Roop Posted October 4, 2020 Author Report Share Posted October 4, 2020 1 hour ago, Bill Yacey said: I wonder if taping up the F holes and applying a medium vacuum source momentarily to the endpin hole would draw the glue in from any cracks? Yes, but you would need real good vacuum control, otherwise you could easily create more splits or even collapse an instrument.... worth pondering! For some time I have had the idea of doing something akin to what is done to fill and seal auto windshield stone chips... Create a vacuum then release filler into vacuum. But can't get my head around the how of the mechanics to doing it on an assembled violin. Quote Link to comment Share on other sites More sharing options...
Evan Smith Posted October 4, 2020 Report Share Posted October 4, 2020 You can build a dam around the void as to contain the glue,, apply glue first,,then you use a soft rubber edged hose or whatever it takes to surround and seal, and pull the vacuum, for long enough according the the glue, and situation, then when the vacuum is released the glue will suck itself in to the void. The vacuum will pull vacuum through the glue lying on top of the void as long as it is liquid. The reservoir of vacuum under the glue will then suck it into place. If glue is injected into the vacuum too far from the destination,, it will boil as it travels to the void, and then the vacuum will have been greatly reduced by the time it finally gets there. A hypodermic needle inserted into the hose next to the void will also allow glue to be applied moments before the vacuum is released. More wandering thoughts. If you pull vacuum on a violin it will pull the arch joints so tightly together,, no glue would be able to enter,, unless of course something on the inside was holding it apart. That is one thing I've never done,,, tried to collapse a fiddle with vacuum,, without a sound post,,, it has crossed my mind though,,, hmmm,, thinking of a sacrifice,,,,hmmm... could be fun and enlightening? I do hate not knowing for sure. Quote Link to comment Share on other sites More sharing options...
Bill Yacey Posted October 4, 2020 Report Share Posted October 4, 2020 This is why I suggested a medium vacuum, enough to create a little bit of negative pressure at the crack opening, and then immediately removed when the glue is drawn into the crack. Using air pressure to push the glue into the crack might work, but it might tend to gel the glue too quickly Quote Link to comment Share on other sites More sharing options...
David Burgess Posted October 4, 2020 Report Share Posted October 4, 2020 28 minutes ago, Evan Smith said: That is one thing I've never done,,, tried to collapse a fiddle with vacuum,, without a sound post,,, it has crossed my mind though,,, hmmm,, thinking of a sacrifice,,,,hmmm... could be fun and enlightening? I do hate not knowing for sure. Shouldn't be difficult, but a vacuum pump would be less messy. Atmospheric pressure collapsing a steel drum: Quote Link to comment Share on other sites More sharing options...
HoGo Posted October 4, 2020 Report Share Posted October 4, 2020 What about washing any dirt or old contaminants with simple distilled (deionized) water? Relatively safe for finishes and after some cleaning the HHG will likely wet the joint better as well. Quote Link to comment Share on other sites More sharing options...
Jeff White Posted October 5, 2020 Report Share Posted October 5, 2020 Matt, I'm sure you could get the glue all the way through by manually working the sides. I would take a small amount of hide glue out of my jar and dilute it a bit. When both are heated well, just start with the diluted glue to get it through and then follow with full strength. Quote Link to comment Share on other sites More sharing options...
Felefar Posted October 7, 2020 Report Share Posted October 7, 2020 Insert toy balloon through endpin hole. Inflate balloon until crack just starts to widen. Push glue into crack, deflate and extract balloon. Clamp and let dry. It worked when I did it. Quote Link to comment Share on other sites More sharing options...
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