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Ground on inside of instrument


fiddlewallop
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The question of the inside treatment is controversial. I used vernice bianca on the past, now I leave the inside wood untreated.

In the Dartington Violin Conference, 1995, when Sam Zygmuntowicz's was asked about inside treatment used in instruments he had studied he replied:

"Carl Becker certainly thought that someting water soluble was used. Renè (Morel) thought that something resinous was applied; they're usually dirty so it's quite hard to tell. Personally I can't resist the opportunity to make some effect on the inside, so I do use something, different things. And yes it does effect the sound because it changes the way the plate vibrates". (I added Morel, I think when he said Renè he was talking about Renè Morel).

Sacconi mentions that there is something water soluble inside well preserved Strads.

And on the Journal of the VSA, vol. XX, no. 3, when asked if he seals the inside of his instruments, Frank Ravatin answered that:

"Yes, I do seal using a very light sealant. I don't seal with linseed oil - that would be a mistake. I won't speak about varnish because otherwise we'll get into complicated things."

Peter Goodfellow mentioned on FACEBOOK that he uses egg white and expose the inside of the instrument to UV.

But if you are making your first instruments, forget it and focuse in the archings, f hole, in a good model, corners, scroll, set up etc. Prior to move to such subtleties it is better mastering the basics, and that's already a lot of work.

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Thanks for this feedback. Interesting topic. There was quite a few informative discussions about VB in the past.

Sacconi probably mentions this, but when opening a Strad, I wonder if there was any color detected on the inside of the instrument? If it was just a clear ground layer applied, it would probably be difficult to tell if there was a faint color due to the 300 years of dirt accumulation.

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Do you mean a sealer (first contact with the wood) or a ground? If you mean a sealer, I have had the same question in my mind. I am looking forward to the range of opinions that will follow!

Hi scordatura,

Yes, I meant as a sealer for the inside of the instrument.

However, I began to wonder if vernice bianca could also be used as a ground. More specifically, if an egg white based ground would accept an oil varnish applied over it.

I began wondering about this because Mr. Darnton mentions in one of his essays that you could use a shellac based ground for an oil varnish. However, I began to question the shellac ground due to its tendency to crack due to its brittle nature. Perhaps, the elasticity of the varnish would permit the shellac based ground to crack without destroying the finish? I would suspect that the shellac on an instrument would be more susceptible to cracking due to the vibrations, then would, say, a piece of furniture which is not subjected to vigorous vibrations.

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Hi scordatura,

Yes, I meant as a sealer for the inside of the instrument.

However, I began to wonder if vernice bianca could also be used as a ground. More specifically, if an egg white based ground would accept an oil varnish applied over it.

I began wondering about this because Mr. Darnton mentions in one of his essays that you could use a shellac based ground for an oil varnish. However, I began to question the shellac ground due to its tendency to crack due to its brittle nature. Perhaps, the elasticity of the varnish would permit the shellac based ground to crack without destroying the finish? I would suspect that the shellac on an instrument would be more susceptible to cracking due to the vibrations, then would, say, a piece of furniture which is not subjected to vigorous vibrations.

I used Darnton's shellac ground so I'll share my experience. I mixed 1 part amber shellac (bulls eye in the can) with 4 parts alcohol. It's very thin and takes numerous coats before it starts to build on the surface. It's such a thin layer I don't think cracking will be a problem, you just want enough to 'seal' not form a thick layer. What I don't like about it is it is too yellow. If I were going to use it again I would mix a small amount of amber with a large amount of colorless bleached shellac so the yellow color would not be so strong.

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A reduction in the hydroscopic nature of the wood could be desirable side effect in addition to possible sonority changes.

datura,

This increased stability need not be the result of coating both surfaces.

Coating both surfaces is the rule in the rest of the woodworking world. I know a number of contemporary makers who do this routinely....One thing to consider is the effects of central heating on the instrument.

Who is listening in? David, Marilyn,Kelvin, PG, Kevin, Guy, MD, Bruce, Greg, Melvin...do you guys coat the inside of the box? Why or why not? Some of you have seen a lot of classic instruments opened up.........

on we go,

Joe

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datura,

This increased stability need not be the result of coating both surfaces.

Coating both surfaces is the rule in the rest of the woodworking world. I know a number of contemporary makers who do this routinely....One thing to consider is the effects of central heating on the instrument.

Who is listening in? David, Marilyn,Kelvin, PG, Kevin, Guy, MD, Bruce, Greg, Melvin...do you guys coat the inside of the box? Why or why not? Some of you have seen a lot of classic instruments opened up.........

on we go,

Joe

Hey Joe.

The slowing of quick humidity changes via a coating would result in less cranky players. For a variety of reasons I have owned instruments that are really susceptable to changes in humidity. Nothing is worse for a player than when you have an important performance and the instrument goes south on you. Some instruments go soggy (unresponsive) in high humidity and conversely get scratchy and fussy when they dry out. This sometimes is in spite of active humidity control efforts! Others tend to be quite stable in a variety of environments.

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My impression is that instruments with high archings are more sensitive to humidity changes, at least there tend to be a larger "fingerboard drop" or "arch rise" when the arch height is larger.

Other factors may be:

1. Bare neck heel, and orientation of the grain there

2. The properties of the back plate and wood. Slab cut is probaly worse than radial cut wood. The amount and depth of flames might play a significant role.

3. How much varnish and sealer there are on the instrument.

One layer of a sealer is not going to be much resistant to exchange of moisture. There are some nice data in the "Encyclopedia of Wood" on the subject.

Letting the fiddle lie with the case open in the concert environment for an hour or two may help in stablizing an instrument for a performance.

Using it for a while just prior also helps. Getting the neck and strings up to an equilibrium before the performance. A player friend use to keep his hands over the strings after tuning the fiddle, helps keeping it in tune. A bigger problem for Hardanger fiddles than for a violin, due to more strings, and the gut. More like baroque violins with guts I guess.

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Hey Joe.

The slowing of quick humidity changes via a coating would result in less cranky players. For a variety of reasons I have owned instruments that are really susceptable to changes in humidity. Nothing is worse for a player than when you have an important performance and the instrument goes south on you. Some instruments go soggy (unresponsive) in high humidity and conversely get scratchy and fussy when they dry out. This sometimes is in spite of active humidity control efforts! Others tend to be quite stable in a variety of environments.

Don't forget that if it's slow to take on humidity when sealed up, it'll be slow to dissipate humidity through that same moisture barrier as well, and that may not be a good thing if it's exposed to high humidity for awhile.

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Don't forget that if it's slow to take on humidity when sealed up, it'll be slow to dissipate humidity through that same moisture barrier as well, and that may not be a good thing if it's exposed to high humidity for awhile.

True but anyone who is storing an instrument in extreme humidity conditions for an extended period of time is asking for big problems!

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David, Marilyn,Kelvin, PG, Kevin, Guy, MD, Bruce, Greg, Melvin...do you guys coat the inside of the box? Why or why not? Some of you have seen a lot of classic instruments opened up.........

Nothing on the inside of mine. I'm trying to avoid anything that might stiffen the wood, so I can make them thicker. Better for long-term resistance to distortion, I think.

Most thin coatings aren't a very effective water vapor barrier anyway, except for aluminum film (like on the inside of crunchy snack food bags), or paint incorporating aluminum flakes. Wax does OK too, if there are no discontinuities in the coverage. It would be fun trying to glue cleats to a wax-treated surface. :lol:

Old fiddles? I'll guess there's some rosin buildup, and some grime (like the stuff that comes off on the cloth when you clean your windows on the inside). Don't know beyond that. Haven't noticed anything water soluble except where there had been repairs. Then, I'm guessing it was glue. At one time, we weren't careful to mask off the surrounding area when gluing cracks.

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I would like to hear more about this. Why willow blocks and linings would encourage worm damage? And what substance would you use as a sealer to prevent worm damage ?

Hi 'MikeC',

Willow is quick to take on moisture. It is very prone to wodworm attacks. A sealer prevents it. I use thin spirit varnish on the inside.

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Most thin coatings aren't a very effective water vapor barrier anyway, except for aluminum film (like on the inside of crunchy snack food bags), or paint incorporating aluminum flakes. Wax does OK too, if there are no discontinuities in the coverage. It would be fun trying to glue cleats to a wax-treated surface. :lol:

I hate to disagree, but I have extensive experience in this regard. My former employer made cellophane, which is pure cellulose made less brittle by adding glycerin or one of the glycols. Uncoated, it is highly permeable to moisture vapor. Among the coatings (too thin to measure mechanically) that DRASTICALLY reduce this moisture vapor permeability are nitrocellulose lacquer and Saran resins. Some of the formulas included resins that can be used in varnish. These coatings made the film suitable for bread wrap and most snack food wrappers. And we did daily testing for QC purposes.

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Have there been any scientific investigations into internal coatings? Or are the opinions just faith based? :huh:

Claire Barlow had opinions on the matter based on electron microscpy, and possibly some chemical analysis, done to wooden samples from interiour of some Strads. I haven't read her articles in detail. Maybe something are said in them. Bruce Tai might have read these.

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Mostly faith-based. Anecdotally, I met a guitar maker a few years ago who trained in Germany. He told me that the person who trained him also made violins and shipped them to the U.S. He said that there were problems with cracks developing during shipping until he started coating the insides. Then no more cracks. I can't confirm the story.

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