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PVA glue does creep over time!


baroquecello
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I just wanted to add something to a recent discussion regarding PVA glues and violin making, but couldn't find the topic when searching.

 

Some were doubting that this kind of glue creeps. Well, I just had the pleasure of taking apart a student violin that I thought was repaired by an amateur using PVA-Glue. Turns out that this 1/2 size violin, german made, coated in a thick Nitro varnish, I suspect made in the 70ies or 80ies, was glued up from the start with pva-glue. It surprised me, because the violin wasn't that badly made at all, for a factory violin: all parts fit well, glueing surfaces quite clean and with good contact, so it seems such a waste that it was glued with pva, especially since it was one of the better sounding beginners instruments the music school I teach at had. The reason it got thrown away, was that slowly over the decades of being under tension, the neck projection had fallen. The neck was slowly moving out of the violin. The neck root had developed a slight overstand to the button, I suspect not much more than 0,25 MM. Possibly also because of other creeping processes, the projection had become so low on this violin, that bowing was problematic and tail pieces with built in fine tuners touched the top. I suspect that if the violin had been glued with hide glue, the neck angle would have still been fine. But even if it would have changed, it would have been possible to dissemble this violin to correct the neck angle, even if it were new york style.

 

So yes, I can confirm, PVA glue creeps when under constant stress, even if the glueing surface is large and quite tight like a reasonably well fitting neck. Therefore it is not a good glue for violin making.

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Well, in seriousness, it makes no difference to say here that Titebond is no good for violins.  Those who continue to use it probably do so by necessity.  These makers will continue to argue that it represents a great progress and evolution in glue and violin making itself, or they will say nothing at all, because it's now a known fact that it's not.  

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I admit the couple dozen inst's I made were glued with Titebond or Elmers,  oldest ones are around 40-years old, some the fingerboard height has not changed at all, some have come down for reasons not related to the neck pulling out of the mortice such as not using quality neck wood, too sharp an arch to the top in the neck area, undoubtedly other reasons. I'm not defending use of either gluing method, I didn't have the thought of selling an inst when I was making them and still have almost all of the inst's except for a few sold to friends. I started making inst's as a hobby at an age when professional makers were thinking about retiring. I think convenience here using  PVA  is justified.  

 

Not Telling, I protest the use of photos of me without my permission-

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I think convenience here using  PVA  is justified.  

 

 

Of course it is!  You do you, Fred.  It's so awesome that you have made all of these instruments and also your unique varnish making technique seems to yield great results.  I got scared to go around playing with chemistry I don't understand when I, completely by chance, saw MacGyver make a thermite blowtorch out of iron oxide, aluminum, and magnesium.  These are all elements that potentially would be useful for pigmenting varnishes, and I was considering using at least two of those ingredients together until that point.  You know how to do that stuff (more or less) safely and I admire you for that.  I hope you know that I thoroughly enjoy your thought-provoking posts on these boards and the fact that you're 90 years old adds to that enjoyment.  I personally find it nearly impossible to plane down anything to perfection with my 20/20 eyes, and I have a hard time seeing how it's done on the length of a cello or bass by anyone.  And yet some do have that skill.  My comment was more aimed at professional makers who are in the habit of using pva and justifying it by saying that it's actually better than hide glue.  

 

And yeah, Mike Jones is right that an edit is called for; the photo is of someone charged with a serious crime who happened to be a successful dealer here in the midwest.  What he's being charged with by the Great State of Nebraska is pretty much the worst thing someone could do to a kid, other than if he had killed her.  This is not something to joke about, so I've taken the photo down.  Sorry if I offended anyone by posting that.

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Conor, I realize i  got age and calendar dates mixed- I'm 90, made my first inst (guess, no label) around age late 60's.  Where did the time go-  fred

Dang it, Fred, I'd consider it to be a high privilege to be where you are. Maybe I'll still have a little to contribute when I'm 90, but more likely not, from having burned the candle at both ends for too many years.

 

I'm only in my mid 60s, and fully realize already what a hard row it is to hoe to continue learning, and moving forward.

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Sorry, didn't know who was in the photo. Not something to joke about.

 

I should add that the present PVA glues have been changed chemically from a few years ago. In the past I was able to convert them so they were only soluble in alcohol and the present ones this is not easily done. Usually such changes are for increasing profit, not quality. fred

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