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"Hardened" bridges...

Discussion in 'Setup & Repair [DB]' started by Damon Rondeau, Jul 22, 2003.


  1. Damon Rondeau

    Damon Rondeau Journeyman Clam Artist Supporting Member

    Nov 19, 2002
    Winnipeg, baby
    What do they do to harden bridge wood?

    The catalog I was just leafing through refers to a "special process" for hardening bridge wood, and all the bridges seem to be offered in the hardened and standard versions.

    I'm assuming this is some kind of chemical process, and not case-hardening from air drying?
     
  2. Marcus Johnson

    Marcus Johnson

    Nov 28, 2001
    Maui
    I know a guy who soaked his in thin CA glue, supposedly to keep it from warping. Prolly not what you're talking about.
     
  3. arnoldschnitzer

    arnoldschnitzer AES Fine Instruments

    Feb 16, 2002
    Brewster, NY, USA
    I've seen these--my thinking is that they are probably immersed in a thin drying oil, then air-dried. Tom Martin wrote in a recent article that the only difference he percieves is that these bridges make a crunching sound when carved. I doubt these "hardened" bridges will warp less than untreated. I wonder, though, if the sound might not be a little brighter...
     
  4. Jeff Bollbach

    Jeff Bollbach Jeff Bollbach Luthier, Inc.

    Dec 12, 2001
    freeport, ny
    Having asked this query on the TOBI list[technology of bowed instruments] the general response was that the treatment process was a closely guarded secret by the bridge manufactures-one possibility was proffered====

    "This may be anecdotal, but I was at the JTL warehouse in Essex, UK some time
    ago. One customer was dropping bridges on a piece of maple to hear the
    "plink". Another was licking the bridges. The "plinker" said he would not do what
    the "licker" was doing, as he understood that French bridges were treated with
    horse urine. As I recall he did not disclose this fact to the "licker"! :)
     
  5. Damon Rondeau

    Damon Rondeau Journeyman Clam Artist Supporting Member

    Nov 19, 2002
    Winnipeg, baby
    I popped over to MIMF and asked the same q, and got a couple responses. The common thread seems to be ammoniation, but one guy says the Germans deny anything having to do with horse piss. (This one reminds me of the reputed method old-timers used to slow down their hide glue. "Need a little urea? I'll show you how it's done, youngster!!")

    One guy who had been through a German bridge plant in the early 80's mentioned the use of calcium silicate as hardener and "tanner". Now I'm wondering what the heck kind of stuff calcium silicate is...
     
  6. Aren

    Aren

    Jul 18, 2003
    Fort Wayne, Indiana
    I met a guy at a bluegrass festival that had several rosewood bridges for sale. Being a harder wood, how well do you think those would work?
     
  7. Damon Rondeau

    Damon Rondeau Journeyman Clam Artist Supporting Member

    Nov 19, 2002
    Winnipeg, baby
    I'm certainly no expert -- amateur enthusiast / hack is a more descriptive term -- but I'll offer the opinion that a rosewood bridge wouldn't sound so good. Too dense, too heavy. The bridge's job is to transmit the energy of the vibrating string through to the instrument, so you want something light and resonant to do that. At the same time, you want something strong to withstand the string tension.

    There's a reason why string instruments mostly use quarter-sawn Bosnian maple for bridges. It does the job admirably and there are generations of experience in how to process it from tree to instrument.
     
  8. arnoldschnitzer

    arnoldschnitzer AES Fine Instruments

    Feb 16, 2002
    Brewster, NY, USA
    I don't like Bosnian maple for my bridges. I prefer Romulan.
     
  9. mje

    mje

    Aug 1, 2002
    Southeast Michigan
    I hear the've upped the import duties on Romulan hardwoods, Arnold. Something to do with Canadian quotas...

    I would think the ideal bridge material would have very low mass and very high stiffness; has anyone experimented with the Moses graphite bridge?
     
  10. sean p

    sean p

    Mar 7, 2002
    eugene, oregon
    steve mosher makes these here in eugene and i have a friend with one on his cheap bass. when we can get together i'll check it out and get back to y'all.

    sean p