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Thread: Finish impact on resonance?

  1. #1
    Every day is a gift. Sheila Lagrand's Avatar
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    Default Finish impact on resonance?

    As I venture out into the big, broad world of mandolin aficionados, I stumble over discussions of the contributions of finish to the resonance of an instrument. What is the latest thinking of the impact of varnish vs. nitrocellulose vs. consecrated infant's spittle on resonance and tone?
    Now, what was I after when I wandered in here?

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  3. #2
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    Default Re: Finish impact on resonance?

    Well, I suspect there'll be a bunch of replies here, so I'll start by saying mandolins with many finishes, probably tot spit too, can sound good. But generally nitrocellulose may not be quite as resonant, woody and open sounding as varnish, and is more durable. This said, nitro can still have those sound qualities.

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  5. #3
    Adrian Minarovic
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    Default Re: Finish impact on resonance?

    General impact of finish is that it adds weight more than anything else and weight is dampener of resonance. So if you keep it very thin the impact is minimal and generally same for any kind of (standard) finishing material, poly, nitro or oil/spirit varnish. There's a wide range of properties of different varnishes or lacquers and they overlap so very few generalizations can hold water.
    With this in mind it's mostly about method of aplication (and care/skill of the builder), some methods necessarily apply thicker layer some keep the build up minimal (like french polish). Some builders can apply very thin lacquer layer while some (factories) apply it very thick just to be safe.
    Adrian

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    Default Re: Finish impact on resonance?

    How the finish lays on the wood is paramount. Is it a coating or is it penetrating and becoming part of the wood? The wood itself is also a factor.


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  9. #5

    Default Re: Finish impact on resonance?

    The real rabbit hole was first opened in the violin world, and probably persists, even though relevant measurement tech has evolved, and made new instrument design a bit more scientific. Mandolin finishes are market-driven, and some buyers like very high gloss, dramatic wood grain or even durability. Many instrument types with soundboards, like Asian, Mid-Eastern and pianos, have no finish at all in the important areas, and often heavy or encrusted finish elsewhere.
    To a factory, a finish requiring the least number of steps, least time, and ease of application that still looks attractive to most buyers. To hand-builders, a finish that demonstrates time and skill. I think that the acoustic tuning is done before there’s any finish, which should tell you something.

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    Moderator MikeEdgerton's Avatar
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    Default Re: Finish impact on resonance?

    In my book Adrian pretty much has it right but I hadn't considered consecrated infant's spittle before now.
    "Bargain instruments are no bargains if you can't play them". These are the words of J. Garber.

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    Registered User Lane Pryce's Avatar
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    Default Re: Finish impact on resonance?

    Just curious but are nitro finishes ever removed in favor of one of the varnish finishes?
    J.Lane Pryce

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    Default Re: Finish impact on resonance?

    Quote Originally Posted by MikeEdgerton View Post
    In my book Adrian pretty much has it right but I hadn't considered consecrated infant's spittle before now.
    I felt honor-bound to bring something new to the discussion.
    Now, what was I after when I wandered in here?

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    Default Re: Finish impact on resonance?

    Quote Originally Posted by HoGo View Post
    General impact of finish is that it adds weight more than anything else and weight is dampener of resonance. So if you keep it very thin the impact is minimal and generally same for any kind of (standard) finishing material, poly, nitro or oil/spirit varnish. There's a wide range of properties of different varnishes or lacquers and they overlap so very few generalizations can hold water.
    With this in mind it's mostly about method of aplication (and care/skill of the builder), some methods necessarily apply thicker layer some keep the build up minimal (like french polish). Some builders can apply very thin lacquer layer while some (factories) apply it very thick just to be safe.
    When I got my Big Muddy mandola, I emailed Mike Dulak about how to take care of it, as the finish is so different from my other mandolins. He said, "yeah I don't like to inhibit the wood with excess finish." I love the way that mandola sounds.

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  19. #10

    Default Re: Finish impact on resonance?

    Quote Originally Posted by Sue Rieter View Post
    When I got my Big Muddy mandola, I emailed Mike Dulak about how to take care of it, as the finish is so different from my other mandolins. He said, "yeah I don't like to inhibit the wood with excess finish." I love the way that mandola sounds.
    I have a Big Muddy mandola and it was pretty open from day 1. Light nitro.

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  21. #11
    Adrian Minarovic
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    Default Re: Finish impact on resonance?

    I must correct myself (after note from Dave Cohen who knows this stuff more than most folks here). I tried to simplify my wording and somehow it can be understood as added mass causes dampening, which is not generally true. I meant to say that added mass of the finish material on wood causes higher damping which can be bad to instruments tone, which was what I think the OP asked about.

    For more education Dave suggests (I read many years ago and will have to read again to refresh my memory):
    Schleske, M.; "On the Acoustical Properties of Violin Varnish"; CAS Journal, Vol. 3, No. 6 (Series II); Nov., 1998. CAS stands for Catgut Acoustical Society.
    Adrian

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  23. #12

    Default Re: Finish impact on resonance?

    Michael Dresdner once told me that it didn't really matter what the finish was when it came to thickness. If it was too thick, regardless of substance, it impacted the sound in a negative way. If it was thin enough, regardless of the substance, it didn't have any negative effect. I can't recall the finish thickness, measured in mils, but it was quite thin.
    As a violin maker I am in a trade full of people who think that the secret of Stradivarius is solely related to the ground or varnish, but I tend to agree with M. Dresdner.

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    Adrian Minarovic
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    Default Re: Finish impact on resonance?

    Quote Originally Posted by Lane Pryce View Post
    Just curious but are nitro finishes ever removed in favor of one of the varnish finishes?
    I don't think many folks do it intentionally. I did that on F-9 few years ago but that mandolin got complete overhaul of everything from arching correction, tonebars, graduations and reset of failed neck joint.
    It's hard (or close to impossible) to tell whether given finish makes a mandolin sound bad and refinish will improve it. In many cases the poor sounding instruments are also poorly graduated (mostly too thick) and refinish takes some wood and makes them sound a bit better or more responsive and more often than not refinish comes with new setup and that alone can change the way mandolin feels so for many refinish from "lesser" finish to varnish is considered step up...
    The spirit varnishes can be so dangerously close in appearance, material properties and thickness of layer to lacquers that one can sometimes hardly tell what finish is used on instrument by just looking. And on violins it is similarly hard to tell apart oil and spirit varnish without chemical analysis (or at least some help of UV light). Folks often think shiny "glassy" finish is spirit while one with softer luster must be oil varnish and that is completely wrong. Best violin restorers use spirit varnishes for finish touch up almost exclusively (also on oil finishes) and can often do it in a way that noone can tell where the damage was mimicking all parameters of original finish.
    Adrian

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  27. #14

    Default Re: Finish impact on resonance?

    Adrian brings up another factor: refinishing. Just as builders and restorers prefer glue that can easily be removed for repairs, they would favor a finish that can be touched up or maintained. This lets out the easy, durable ‘plastics’. The poster on Feb. 28 with a delaminating probably polyurethane finish presumably has figured out why there are problems with repair or removal. Evolution in automotive finishes demonstrates how durability trumped repairability a generation ago. Finishes that could be polished, blended, and removed were replaced by catalyzed base-coat-clear coat wonders. Now, our cars don’t need annual polishing, don’t get dull, crack and blister, so why not a mandolin or a tuba?

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    Registered User Lane Pryce's Avatar
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    Default Re: Finish impact on resonance?

    "I did that on F-9 few years ago"

    I remember that F9. Great job on its restoration. Where did that one end up?
    J.Lane Pryce

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    Default Re: Finish impact on resonance?

    Conventional wisdom has always been that light finishes mean more sound, and heavy finishes mean less.
    Everything else has been a matter of debate for at least three centuries.

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    Default Re: Finish impact on resonance?

    Quote Originally Posted by Richard500 View Post
    .........Now, our cars don’t need annual polishing, don’t get dull, crack and blister..............
    You have definitely not seen my car!

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    Default Re: Finish impact on resonance?

    Michael Dresdner has been mentioned here and I note that he is a regular contributor to one of my woodworking magazines as a finishing expert. His knowledge on the subject is extensive. I cut out and keep his columns in a file folder labeled "Finishing". A great reference.
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  37. #19

    Default Re: Finish impact on resonance?

    Finishing will be on my mind too, before long. I'm doing my first build, a Saga kit. I recently finished a StewMac baritone ukulele, and used my old favorite, Formby's Tung Oil varnish. I love how easy it is to apply, and how forgiving it is. If I have to touch up a spot for any reason, just sand a bit and rub in a few coats, no problem. I like the low-gloss but rich look it gives. The first time I used it was refinishing a cheap National branded copy of a Les Paul, replacing the chipped black acrylic lacquer. As it turns out the top was pretty cheap laminate, but after a little stain & varnish, looked like a respectable guitar. The Uke is real pretty walnut and looks lovely, no stain.

    I also like that with this kind of finish, you can (and should) rub in some oil now and then. And it doesn't get ruined if I pick up the instrument aft

    The Saga isn't so pretty. The top of course is spruce and looks mostly OK but with a short brown streak by where the bridge will be. (Close-grained, 22/in.) The back is maple that's figured but ... well ... it won't win any beauty contests. So I'm wondering whether to continue with the Formby's, or try something new.

    I'd seen videos of makers talking about how finishes matter, one specifically mentioning the finish would improve the tone after a few years (on an old mando he'd made a new top for.) But I wonder if you can ever tell which of a dozen things really make the difference. So, I'll be interested to follow this thread. Frankly I hope the consensus is correct, that it doesn't matter much if the finish is light. I'm not particularly talented or experienced in this department.

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