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Sound properties of varnish

Discussion in 'Setup & Repair [DB]' started by Damon Rondeau, Dec 26, 2002.


  1. Damon Rondeau

    Damon Rondeau Journeyman Clam Artist Supporting Member

    Nov 19, 2002
    Winnipeg, baby
    There have been a few threads recently relating to finishes. They've had me thinking and doing some reading.

    Specifically, I'm wondering about the sound properties of varnish. Because this whole topic can so easily run aground on terminology, let me say that I understand varnish to be resin (tree resins, synthetic resins) cooked in oil (linseed, tung, sunflower, etc.); it cures through oxidation and its solvent is mineral spirits (turpentine, paint thinner.) Varnish mixed with more oil and solvent is oil varnish.

    In my reading so far about varnish and violins, there's much talk about transparency, resin hardness, brushing qualities and the like. All of this is easy enough to relate to. I wonder, though, what the thinking is about the aural properties of the components -- the resins and oils. Anyone care to share a thought or tip me to some reading sources? Bass-focused info is, of course, even better.

    I realize that the type of aural effects likely to be brought about through small differences in varnish composition are probably small compared to other things like wood and craftsmanship, but this is the sort of thing my brain has me wondering about...

    thx,
    Damon
     
  2. When it comes to violin type varnishes, there are just about as many different opinions as there are makers. In the beginning, stringed instruments did not have varnished exteriors. IMO, the main reason varnish was added was simply to keep dirt and moisture from damaging the appearance of the wood. There is no question that any varnish changes the sound of an instrument. Like many makers, I prefer to string up and play an instrument for a while "in the white" before the varnish is applied. As soon as an instrument is varnished, the sound changes, and it continues to change over time as the varnish dries. This may be one of the reasons why instruments sound better after being "played in" or "aged". Many times an instrument sounds better (to me) in the white than after it is varnished.

    I don't know of any particular book I would recommend on varnish, but most large public libraries will have one or two books on violin varnish. There is also quite a bit of information available on the net. Just do a search for "violin varnish". One of the favorites of violin makers today is the William Fulton Terpene varnish. There is a SCAVM article by Fulton available for reading on the internet.
     
  3. arnoldschnitzer

    arnoldschnitzer AES Fine Instruments

    Feb 16, 2002
    Brewster, NY, USA
    Good exposition, Bob!

    For years there has been a controversy over which sounds better--oil or spirit (alcohol-based) varnish. For my money, oil varnish is better suited to a bass, where the plates vibrate with a lot of amplitude, because it is more flexible. It is also less likely to chip and craze. Of course there are different resins in various oil varnishes, i.e., copal, amber, rosin, etc. Some impart a harder film than others. To me the ideal varnish is protective and tough on the surface, but remains somewhat flexible over time.

    Unlike Bob, I don't string up basses in the white. I find they sound so different when varnished that evaluating in the white does not give me any useful information.

    You might check out Joe Robson's website: WWW.VIOLINVARNISH.COM which contains lots of info.
     
  4. Damon Rondeau

    Damon Rondeau Journeyman Clam Artist Supporting Member

    Nov 19, 2002
    Winnipeg, baby
    Thanks, gentlemen, for the words of experience.

    I had sort of intuited on my own that what you're looking for is that more flexible film coating that still serves the protection function (whaddaya know, another tradeoff situation; they're everywhere in life, aren't they?). From the non-instrument world of finishing wood stuff, I knew that spar varnish, for example, is formulated for flexibility to accomodate the greater movement of wood in outdoor conditions (spar varnish = tung oil and I can't remember what resins.)

    The question about the acoustic properties of the varnish components themselves (resins, oils) is the sort of thing that can come up when you're working on your own, trying to understand particular situations from a general theory standpoint and from what you already know. It's the sort of situation where, even if you know a lot and are pretty good at what you do, you can still do/think some goofy stuff!

    Yet another argument for working with teachers, I guess....

    So here's another one from the same ballpark -- any opinions on the acoustic properties of various sealing substances? I was looking at some luthier's website (can't remember who) where there were some very interesting electron microscope photos of old Strad violins, showing the thin sealer layer composed of various fine-ground minerals (can't remember what holds the minerals together.) Somehow over time we began to really fancy a smooth feel in finished surfaces and sealers I guess began to be optimized for creating good smoothing conditions. I guess that leads to the whole raised-grain-feel versus smooth-feel that, in another thread, Jeff Bollbach talked about with the unfortunate Mr. Veltmann....

    Thanks, guys, for indulging this person from the northern hinterland who wonders about these things...
     
  5. I guess I'm just curious how it will sound even though I know It's not going to sound anything like that when the varnish goes on. :)
     
  6. Tumbao

    Tumbao

    Nov 10, 2001
    FL
    good'ol1, Bump!
     
  7. Dr Rod

    Dr Rod

    Aug 19, 2005
    I read yesterday that some makers like the sonic qualities of craquele varnish, because it doesn't straightjacket the top.

    Comments?
     
  8. banjo-tom

    banjo-tom

    Mar 9, 2006
    Toronto
    Thanks for bringing up this topic up Damon.
    This is just what I need to read!!
    It closely resembles the situation I find myself with.
    This thread will definitely add to the scare info available regarding wood finish for DB
    Tom
     
  9. nicklloyd

    nicklloyd Supporting Member/Luthier

    Jan 27, 2002
    Cincinnati, Ohio
    Where did you read this?
     
  10. Allan Santos

    Allan Santos

    Dec 17, 2005
    Hi Arnold,

    What does craze mean?

    Thanks,

    Allan
     
  11. Dr Rod

    Dr Rod

    Aug 19, 2005
    Hey Nick

    I read it on strad magazine, the makers that claim this are a couple from Connecticut I think, the Moes'. They don't build basses, but their cellos are played by big shots.
     
  12. arnoldschnitzer

    arnoldschnitzer AES Fine Instruments

    Feb 16, 2002
    Brewster, NY, USA
    Crazing is cracking of the finish. it looks like the skin of an alligator. It is generally caused by application of incompatible materials. Sometimes it happens when varnish is applied with inadequate dry time between coats. Then the varnish dries out unevenly, from the outside in, and cracks.
     
  13. KSB - Ken Smith

    KSB - Ken Smith Banned Commercial User

    Mar 1, 2002
    Perkasie, PA USA
    Owner: Ken Smith Basses, Ltd.
    Arnold, when you get a minute, take a flashlight and magnifier glass and look at the top of my Gilkes there for restoration. I recently noticed this 'crackling' under a flashlight and magnifier glass that was not visible to the naked eye. I don't see any on the back, ribs or neck/scroll, just the top. This is the 200 year old top that has never cracked but the varnish under close amplified inspection show this effect.