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Thread: Mystery corrosion - anyone know why?

  1. #1
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    Default Mystery corrosion - anyone know why?

    Hi Folks,

    This keeps happening:
    Click image for larger version. 

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    This has occurred maybe 3 times in the last 2 years and I don't think ever before over the previous ~18 years I've had this instrument. I don't check-in with this mandolin all that often. After some time passes, I open the case and 1 or more strings has rusted through and broke. I wipe-up, put on new strings, play a bit, and next time strings are like this again.
    Important change is that we moved from Colorado to Goleta, CA 1.5 years ago. However, nothing like this has been happing to my other 3 mandolins or guitars, etc.
    At first I thought it might be something from my fingers but then the pattern is not right for that...and it's getting into the frets (and again not happening to other instruments).
    Now I'm wondering if it's something in the case that's activated by somewhat higher humidity. We get some salt fog here sometimes also.

    Anyone have an idea what's causing this corrosion?

    P.S. I hope this post fits in this forum. I haven't logged into MCafe in many years. Maybe I'm turning a page.

  2. #2
    Moderator MikeEdgerton's Avatar
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    Default Re: Mystery corrosion - anyone know why?

    It would appear that the pickguard is celluloid and it is off gassing and corroding the strings. Do yourself a favor and remove the pickguard before it causes you any other issues. I wouldn't store it in the case.
    "It's comparable to playing a cheese slicer."
    --M. Stillion

    "Bargain instruments are no bargains if you can't play them"
    --J. Garber

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  4. #3
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    Default Re: Mystery corrosion - anyone know why?

    That is an early symptom of your pickguard starting to deteriorate. A lot of the old Gibson pickguards start to emit a gas, then crack, and finally turn to powder. The gas is corrosive to metal.

    I have noticed that the deterioration sometimes starts where some pickguards have a metal rod that runs parallel to the fingerboard that is embedded under a reinforcing strip. The rod starts to rust, then reacts with the plastic, and sets off a slow chain reaction.
    I arrested the process in one by removing the rod and reinforcing strip, cleaned the rest of the guard, and installed a new reinforcing strip made of ebony and left the rod out. In most cases, though, the guard will have to be replaced.

    I've made several replacement guards over the years. I have to make one for a Gibson arch top guitar this week. Unfortunately, the material is expensive, but I have some in stock. You are welcome to pm me if you wish.
    Last edited by rcc56; Jan-16-2022 at 12:27am.

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    Registered User Greg Mirken's Avatar
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    Default Re: Mystery corrosion - anyone know why?

    Yeah, no mystery at all. As the pickguard deteriorates it releases nitric acid. Once it starts, it accelerates.
    There’s not much you can do. Remove the guard before those frets are totally ruined.

    Greg Mirken
    Shade Tree Fretted Instrument Repair, retired
    Nevada City, California

  7. #5
    Likes quaint instruments poul hansen's Avatar
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    Default Re: Mystery corrosion - anyone know why?

    What make and year is it? Gibson?
    Kentucky KM-805..........2 Hora M1086 Portuguese II(1 in car)
    Hora M1088 Mandola.....
    Richmond RMA-110..... .Noname Bearclaw
    Pochette Franz Janisch...5 Pocket............Alfredo Privitera pocket
    Puglisi Pocket 1908........Puglisi 1912.......Puglisi 1917
    3 Mandolinetto ..............C.Garozzo
    1 Mandriola...................Cannelo G. Mandriola...Böhm Waldzither 1921
    Johs Møller 1945............Luigi Embergher Studio 1933
    Marma Seashell back......Luigi Embergher 5bis 1909

  8. #6
    Moderator MikeEdgerton's Avatar
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    Default Re: Mystery corrosion - anyone know why?

    Quote Originally Posted by poul hansen View Post
    What make and year is it? Gibson?
    Note the label, the riser block and the patent stamp on the pickguard. It's a Gibson, most likely a Jr by the color and lack of binding on the body.
    "It's comparable to playing a cheese slicer."
    --M. Stillion

    "Bargain instruments are no bargains if you can't play them"
    --J. Garber

  9. #7
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    Default Re: Mystery corrosion - anyone know why?

    By the way, for those that haven't seen this it's a pretty common problem.

    https://www.google.com/search?q=off-...client=gws-wiz
    "It's comparable to playing a cheese slicer."
    --M. Stillion

    "Bargain instruments are no bargains if you can't play them"
    --J. Garber

  10. #8
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    Default Re: Mystery corrosion - anyone know why?

    Not sure if there’s any truth in the view that it only happens on later models. There’s no problem with my ‘15A and my 24 Snakehead but I discovered it on my ‘76 Ibanez a couple of years ago. If it’s happening, take it off before it burns the top. Rumour has it that storage in the open air can reduce the problem.

  11. #9
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    Default Re: Mystery corrosion - anyone know why?

    I think a lot of the issue is storing the guard (and binding in some cases not this one) in a closed case can cause the problem to reveal itself. The problem is that not storing in a case can be disastrous in certain situations as well. My 1921 A doesn't have the issue. It sat under a bed for 40 years or more and I just opened it for the first time in a few years. It's clean. I don't recall anyone ever actually determining an era. It was probably issues with certain batches of guards and there may have been different eras for the problem.

    Years ago I grabbed a set of the notorious Kluson mandolin tuners with the bad buttons that generally deteriorated off a mandolin. This set was pristine like they were brand new. I stored them away in a plastic bag so they would be safe. Six months later they were shriveled and crumbly.

    My guess is that you need to air these guards out now and again. Then there is the entire spontaneous combustion thing regarding celluloid.
    "It's comparable to playing a cheese slicer."
    --M. Stillion

    "Bargain instruments are no bargains if you can't play them"
    --J. Garber

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  13. #10
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    Default Re: Mystery corrosion - anyone know why?

    Yes, the Ibanez guard is sitting on a shelf and looks no different than when I took it off.

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    Default Re: Mystery corrosion - anyone know why?

    Hi Folks,
    Well I certainly came to the right place to ask about this.

    Darryl made this pickguard for me a long time ago. Memory is fuzzy. I think I bought several items from him at once, including a nice repro pickguard for my F5. So I guess I better think about what to do with that F5 guard as well. A difference is that this Ajr guard has been on the instrument constantly - maybe approaching 20 years now. The F5 has seen a lot more action and it's been hard to keep that pickguard in good maintenance, well-mounted, and not rattling. So the F5 guard has spent the majority of those years in the pocket of a case that I rarely use. I sometimes try to get a luthier to tune-up the pickguard and install it again whenever I have frets dressed. But it usually starts to be trouble again pretty soon.

    This instrument is an outstanding '24 Ajr. I sortof rescued it - maybe it's already been 20 years or more now. It was hanging on the wall in a shop in Austin that seemed to specialized in old electric guitars. It was off in the corner and way up there close to the ceiling. The back was coming off and the frets wrecked. I can't remember if there were any strings or bridge. The neck is just perfect and has a similar vibe to my F5. After a luthier in Denver put the body back together and replaced the frets, the sound was amazing. It was the first snakehead A I had played. So I continued to fix it up with a "normal" period tailpiece, and a bridge and pickguard that I got from Darryl. It remains among the best 3 mandolins I've ever owned.

    thanks all for your knowledge and advice

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    Default Re: Mystery corrosion - anyone know why?

    Quote Originally Posted by calebroberts View Post

    Darryl made this pickguard for me a long time ago.
    Are you sure he “made” it for you? From your photo’ it appears to have the “Pat. Pending” stamp so it could well be a period one.

  16. #13
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    Default Re: Mystery corrosion - anyone know why?

    http://www.f5journal.com/reproductions.html

    I think he's made stamps to reproduce the patent stamps on pickguards and bridges.

    - - - Updated - - -

    Any suggestions for how to treat the corrosion on those frets?

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  18. #14
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    Default Re: Mystery corrosion - anyone know why?

    Generally, a minute's rub with #0000 steel wool perpendicular to the frets will take care of it. It doesn't hurt to protect the face of the instrument with a piece of cardboard in case you slip. If that doesn't quite do it, use 600 sandpaper dry, then follow with the steel wool. Then you can clean up with a little naphtha on a rag if you want to.

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  20. #15

    Default Re: Mystery corrosion - anyone know why?

    A dilemma, especially for those wanting cases to maintain humidity, so why not a combo humidifier and chemical off-gas absorber. Bernie?

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    Default Re: Mystery corrosion - anyone know why?

    Darryl has always striven to get the most realistic feel and look to the parts he manufacturers although it never occurred to me that he could duplicate this part of the experience. I've always known he was good but this is pretty impressive.
    "It's comparable to playing a cheese slicer."
    --M. Stillion

    "Bargain instruments are no bargains if you can't play them"
    --J. Garber

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  23. #17
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    Default Re: Mystery corrosion - anyone know why?

    If they are played every day off-gassing in the case won't be as much of a problem.
    THE WORLD IS A BETTER PLACE JUST FOR YOUR SMILE!

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  25. #18
    Likes quaint instruments poul hansen's Avatar
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    Default Re: Mystery corrosion - anyone know why?

    Quote Originally Posted by pops1 View Post
    If they are played every day off-gassing in the case won't be as much of a problem.
    Some people have a bit more than a few instruments, so......
    Kentucky KM-805..........2 Hora M1086 Portuguese II(1 in car)
    Hora M1088 Mandola.....
    Richmond RMA-110..... .Noname Bearclaw
    Pochette Franz Janisch...5 Pocket............Alfredo Privitera pocket
    Puglisi Pocket 1908........Puglisi 1912.......Puglisi 1917
    3 Mandolinetto ..............C.Garozzo
    1 Mandriola...................Cannelo G. Mandriola...Böhm Waldzither 1921
    Johs Møller 1945............Luigi Embergher Studio 1933
    Marma Seashell back......Luigi Embergher 5bis 1909

  26. #19
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    Default Re: Mystery corrosion - anyone know why?

    Quote Originally Posted by rcc56 View Post
    I have noticed that the deterioration sometimes starts where some pickguards have a metal rod that runs parallel to the fingerboard that is embedded under a reinforcing strip. The rod starts to rust, then reacts with the plastic, and sets off a slow chain reaction.
    Hi rc56, thanks for this particular piece of info. The luthier who installed the pickguard for me retained the 1 original mounting pin that was intact and made the 2nd from what appears to be 3/32 stainless rod. The original pin is of course rusty. I think I'll find some more stainless rod and experiment - whether the off-gassing persists after eliminating the rusty pin.

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