'23 Gibson A-style Repair

[Moscow_Joe]

Gentlemen (and Ladies?),

I am new to your site. I am a small time vintage instrument collector and player (not a good one). As such, I do some instrument repair - minor and some pretty extensive work. Primarily I do all the work for myself.

What led me to your site is a recent purchase of a Gibson A-style mandolin in need of some repair. First of all, let me say that I have very much enjoyed the chat and read extensively through many of the strings on the message board. I think that this is probably the best site of it's kind that I have come across. And, although I am not the afficianado that most of you are, the interaction and the quality of the information is A+. Makes me want to build my own mandolin.

Getting back to the real reason that I wrote to you for help - the A-style needing repair. As I said, this mandolin is, I think a 1923. Both the label serial number and production number support that. It has a brown spruce top and birch(?) or maple body. The peg head is the "snakehead" style, with no Gibson logo. From the top, the mandlin is in superb condition. It belonged to the previous owner's grandmother and he said he never saw her playing it. However, age took its toll and it has a couple problems:

-Unlike most of the A-style manolins, this one has binding around the back, as well as front. However, unlike the top white binding, the back is "tortoise shell". While the binding around the top is in perfect condition, the back binding deteriorated to the exten tthat it's crumbling off, leaving the end-grain of the back exposed and causing it to "check". The binding needs to be replaced and sealed to prevent from further damage.

-The deterioration of the binding around the back had something to do with the other problem. The nickel plated metal clamp that supports the pickguard corroded at the point where it was in contact with the back binding. The "hook" part of it actually rotted off. The rest of the clamp shows absolutely no effects of the corrosion. The metal must have reacted somehow with the binding material.

I don't have a vintage mandolin in my collection and would like to repair and keep this one. I think that a Loar era, snakehead A-style would be a nice addition. I need your expertise to answer some questions before I can even start:

-Can anyone tell me where I can obtain faux tortoise binding, thicker than the 1/16" offered by LMI. StewMac doesn't carry it anymore. Before I consider laminating, I would like to see if I can get something thicker.

-The routed channel seems to vary in thickness (depth), probably do to the shrinkage(?)of the top. However, if I get a binding that is slightly over 2mm thick, it should be a happy medium and hopefully fill the channel well. If it's thicker, I can deall with that better than if it's too thin.
-With respect to the finish - can you tell me what finish Gibson used on these mandolins back then?. Is it lacquer, shellac or what? I don't intend to refinish the mandolin but I need seal around the bindin and touch up the checking so that it doesn't crack. Any advice would be appreciated.
- Lastly, is there any chance that I can get a replacement pickguard clamp like the one that rotted off. Does anyone make repro's, if I can't find an original?

Thnaks in advance for any help you can offer.

Thanks,

Joe

[sunburst]

Here's one source for tortoise plastic.

The finish is shellac unless it's after about 1925. You can test with a tiny drop of acetone in an "inconspicuous place". Acetone will disolve, or at least soften lacquer, but won't have any affect on shellac.

There's no replica pickguard clamp on the market. (I need one too.) Sometimes they are on Ebay and elsewhere, but prepare to pay at least $125 or so.

[Michael Lewis]

The corrosion of the metal is due to the nitric acid fumes that were released from the binding as it deteriorated. It was probably left closed up in it's case for years at a time. The gasses tend to accumulate when in an enclosed space. In the open the fumes disipate into the air, generally harmlessly.

[Moscow_Joe]

Thank you all for the information. I guess the clamp will be a problem. I'll keep looking.

[MML]

Moscow-joe, sometimes you can find a whole pick-guard with clamp, or a trashed guard with good clamp. Like a fool I sold 2 of them a few years ago w/clamps for approx $75 each.So keep your eyes open, they show up.

[Moscow_Joe]

Thanks Mike. There was one E-bay a few days ago that went for $291! Bit steep for me at this point, especially when I didn't need the picguard itself.