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PVA Glue has a place in violin making/restoration. Any thoughts?


Nikos Matsablokos
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PVA glues were developed in the 1950's. It would be a real shame if our heirs a few hundred years hence, find that the pva glues deteriorate slowly and that  these lovingly and meticulously repaired and hand made instruments, made with PVA glues, begin to fall apart and lose all significant value. ... and for what... a bit of convenience today?

Hide glue is easy, hide glue works, hide glue lasts, hide glue is proven... I'm sticking to hide glue.

Cheers... Mat

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9 hours ago, CaseyLouque said:

Wouldn't Fish Glue be a good alternative to PVA?
I read that it dosn't suffer from the creep issues of PVA can be reworked with moisture.

Its ready to use in a bottle no heating or wetting required. Similar curing time.

I am not advocating it use over hide glue. I believe hide glue should be used.

But if I had to choose to do a repair on an instrument previously fixed with PVA or fish glue I would rather work with the fish glue.

I'm not an expert on it, but fish glue releases way more easily than hide glue, IME.  That's a very bad thing for repairs. 

I use it only for a few tasks where I want that easy reversibility (i.e. - an intentionally temporary glue joint like a positioning block on a jig, a pillar, etc).  For those uses, I like it.

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8 hours ago, JoeDeF said:

I'm not an expert on it, but fish glue releases way more easily than hide glue, IME.  That's a very bad thing for repairs. 

I use it only for a few tasks where I want that easy reversibility (i.e. - an intentionally temporary glue joint like a positioning block on a jig, a pillar, etc).  For those uses, I like it.

There are MANY different kinds of fish glues. It's impossible to generalize.

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I watched part of the video that the OP posted. One subject that the "Maestro" touched on was using plywood for repairs. While I certainly don't advocate using this willy nilly for all repairs, I do believe that it has a place for repairs on some instruments made by "lesser Gods".

I've been using this for years for certain things. This is what I have in the kit. It's 0.8mm thick, and can be cut with scissors. As with most plywood, it bends better in one direction than the other, but it's quite strong in all directions. I've used it as an overlay for rib repairs on student instruments, and as an overlay "sound post/wear patch" for student instruments (some people advocate not using a soundpost patch for small, fresh cracks).

While this is not the classical inlaid repair, it is totally reversible, doesn't remove original wood, and can provide an economical repair option for student instruments. I'll be waiting for the "purists" to chime in.:D

SCN20211228_56.jpg

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1 hour ago, HoGo said:

There are MANY different kinds of fish glues. It's impossible to generalize.

Yes. I tried fish glue once when I was making guitars, using a go-bar deck, and thought it would be nice to have  a bit more open time.  Later, I wanted to remove the top and it was very difficult.

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59 minutes ago, FiddleDoug said:

I watched part of the video that the OP posted. One subject that the "Maestro" touched on was using plywood for repairs. While I certainly don't advocate using this willy nilly for all repairs, I do believe that it has a place for repairs on some instruments made by "lesser Gods".

I've been using this for years for certain things. This is what I have in the kit. It's 0.8mm thick, and can be cut with scissors. As with most plywood, it bends better in one direction than the other, but it's quite strong in all directions. I've used it as an overlay for rib repairs on student instruments, and as an overlay "sound post/wear patch" for student instruments (some people advocate not using a soundpost patch for small, fresh cracks).

While this is not the classical inlaid repair, it is totally reversible, doesn't remove original wood, and can provide an economical repair option for student instruments. I'll be waiting for the "purists" to chime in.:D

SCN20211228_56.jpg

I use this 0.8mm thick plywood for my viola and violin back plate and ribs because it bends easily and is strong.

No 38 back .jpg

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2 hours ago, FiddleDoug said:

... using plywood for repairs. While I certainly don't advocate using this willy nilly for all repairs, I do believe that it has a place for repairs on some instruments made by "lesser Gods"...I'll be waiting for the "purists" to chime in...

I just put that plywood on my to-buy list, so I guess that means that I am not a purist.  I really could have used it last week to reinforce a rib crack.

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4 hours ago, Brad Dorsey said:

I  just put that plywood on my to-buy list, so I guess that means that I am not a purist.  I really could have used it last week to reinforce a rib crack.

I use an electrically heated violin rib bending iron (actually its aluminum) which has a length of 170mm and it is not quite long enough.  The length of the viola back bend is about 370mm so going in from both ends of the plate doesn't reach a center portion.  But it still seems to work ok.

This very thin birch plywood is a fairly recent invention.  If it been available 400 years ago model airplanes probably would have been made with it instead of the traditional woods.

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3 hours ago, jdevries said:

What about the video's central assertion that hide glue 'dries out' over time and comes loose? Does this have any validity?

I am pretty sure that is rubbish, it depends on the humidity and temperature of course but unlike pva glue instruments like Stradivari's have been time tested for hundreds of years. Of course many of them have numerous repairs but they are obviously still around. 

PVA could be way worse in that matter and nor the "maestro" or we, will know because to make a fair comparison between the two, instruments made using pva would have to last at least 300 years. Hide glue has been time tested and its clear that its a great choice for what we do, pva on the other hand has not. 

So to be honest with you I believe that the "maestro" is full of... and I personally don't trust a thing he says. But that's the way modern society works, YouTube has provided a voice for hacks and pseudoscientists to express their "knowledge" on anything they come up with.

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The science of accelerated aging is well developed and has been in use for many years to test the time durability of adhesives. The two areas I know about are in the construction industry and in book preservation/archival. Both of these areas make extensive use of PVAC adhesives.

It would be a research project to see what accelerated aging tests have been performed on white glues, but I would be very surprised if none could be found. So before dismissing the age durability of PVAC, I think a little more work is needed.

For me, the low creep resistance of interior use white glues is a deal breaker. But as I said, there are versions of it that have good creep resistance.

I am not trying to make a case to use white glues in violins. Just trying to present the science-based properties of it so people can make an informed decision.

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I think the main reason Kimon uses PVA, is simply that he finds it easier to use, being premade and ready to go straight from the bottle.
Using hide glue correctly requires skill and experience, for good results. Many fail at this, and look for the easiest solution in its place.

So rather than learning what to do correctly, do something else, and then make up reasons why their choice is somehow superior.

 

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10 hours ago, jdevries said:

What about the video's central assertion that hide glue 'dries out' over time and comes loose? Does this have any validity?

I think that hide glue failures are often caused by poorly fitted joints.  And I think that these failures are often attributed to the glue drying out, because when the joints separate dry glue is visible, but the real cause is poorly fitted joints.  Hide glue works poorly as a gap filler, but it works very well when there is close wood-to-wood contact.

White/yellow glues work much better that hide glue as gap fillers, making them a better choice than hide glue for poorly fitted joints and inept assemblies and repairs of all types.

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23 minutes ago, David Burgess said:

How are PVA glues used in the construction industry?

The decent sized fireplace mantel areas that work their way towards the ceiling is one instance.  Mostly to stop air leakage from below and above I'd think in addition to keeping the cheap, not really dried properly poplar from moving more than what they'd want.  

A few times over the years I've seen the empty gallon glue jug laying in the trash piles but can't say if that was glue used over several job sites or just one.

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26 minutes ago, Carl Stross said:

Which one - the clear or the tan ?

Clear because it doesn't expand. The tan stuff works too but it foams when it sets which makes a little mess.

I use two flat thin plates and glue their center joint with the Gorilla glue.  I throughly wet the glued top plate and heat it with a heat lamp and then bend it to have a shallow arch.  The Gorilla glue joint withstands this stress, moisture and heat so I doubt anything can happen to it afterward.

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1 hour ago, uncle duke said:

The decent sized fireplace mantel areas that work their way towards the ceiling is one instance.  Mostly to stop air leakage from below and above I'd think in addition to keeping the cheap, not really dried properly poplar from moving more than what they'd want. 

So largely for ornamental finishing work? If the wood isn't properly acclimated, "creep" properties of a glue might actually be an advantage, allowing some self-adjustment as the wood changes in dimension.

27 minutes ago, Marty Kasprzyk said:

Clear because it doesn't expand. The tan stuff works too but it foams when it sets which makes a little mess.

The foaming tan is a urethane, isn't it? What sort of glue is the clear?

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1 hour ago, David Burgess said:

The foaming tan is a urethane, isn't it? What sort of glue is the clear?

The "original" Gorilla Glue is advertised as polyurethane.  I don't see a description of the glue type for the clear... at least from the manufacturer.  They recommend damping the surfaces, as with the polyurethane.  I did see one statement from the manufactuer describing it as a "hybrid" adhesive... but what it's a hybrid of is uncertain.

I have used both, and the clear is much more flexible or rubbery than the original polyurethane glue.  I wouldn't use it for anything important or load-bearing without a lot of testing.

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5 hours ago, David Burgess said:

How are PVA glues used in the construction industry?

There are formulations of PVA, depending on the need for moisture and/or creep resistance, that have been successfully used in boating applications, load bearing plywood walls and composite beams, and fences to name just a few off the top of my head.

These things have evolved quite a bit from the squeeze bottle of Elmer's Glue we used for paper construction projects in kindergarten. >grin<

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