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Permalink Reply by Ron "Oily" Sprague on April 9, 2012 at 5:18pm

Karl,

 

I'm speaking to you as a biologist and geologist on this one.

 

Mother of pearl, or MOP, is the inner shell lining of oysters, some clams, and abalone. It is composed of calcium carbonate, CaCO3, and is both quite soft, being a 3 on Moh's hardness scale (just above talc and gypsum), and quite brittle on edge because it is deposited in very thin layers. You can easily cut it with a not very sharp knife, so imagine what a steel string under tension, being played daily, will do to it. That is the reason it is used for accents, decoration and inlays, because it is very soft and workable, and has a lovely mottled shine, and not for anything load-bearing. I wouldn't try to use it for a nut or saddle, even epoxying several pieces together.

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Permalink Reply by Karl G. Siewert on April 9, 2012 at 6:43pm

That's exactly the kind of answer I was hoping for. Let's hear it for science!

I should have realized that it would be the same material as oyster shell, which I know is essentially the same as chalk. Thank you for clearing it up. Guess I'll be using it as decorative material only!

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Permalink Reply by Ben on April 10, 2012 at 4:56am

I'm inclined to go with Oily's science on this one but you might be interested to know that 2 people have reviewed the product from stewmac. I don't know the actual composite of their material but it has been done to some extent. 

http://www.stewmac.com/shop/Nuts,_saddles/String_nuts/Mother-of-pea...

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Permalink Reply by Ron "Oily" Sprague on April 10, 2012 at 6:02am

Ben,

Thanks! There are indeed suppliers of MOP nuts and saddles, including Stew-Mac, as you've noted. Seems like most of it is coming from Vietnam and other Asian countries nowadays. MOP was used for nuts and saddles primarily on 1920s-era, high-dollar, top-of-the-line, "fancy" Gibson banjos and mandolins, and occasionally on guitars, because of its ability to take a high polish. I've said I think it's too brittle end on, especially for a saddle; another consideration is that it seems to be 2-3 times the cost of regular old bone. There is a way to harden it up some, by exposing it to high heat, which can cause partial recrystallization of the carbonate; maybe that's what's being done by the modern suppliers? So, obviously, people are using it, probably even with success. I personally wouldn't do it.

Anyhoo, the lutherie forums I've looked at all seem to favor bone, for longevity, durability and workability. And pre-slotted bone blanks are pretty cheap, around $3-5 per on eBay, and around $5 from the various luthier supply houses. Of course, if you wanted to, you could go to the local butcher's, get you a cow leg bone for next to nothing, bleach it, degrease it, dry it, and cut it up into a fair number of saddle and nut blanks.

Actually, now that I'm thinking about it more, if Karl has enough material, there's really nothing to stop him from at least trying one, aside from me giving him scientific reasons why I personally wouldn't. These are CBGs, often made from found materials, so why not give it a whack? Worst that can happen is you have to replace a nut or saddle with bone. Or a good old bolt.

Geologists are also well known for appearing wishy-washy, because we are trained to hold multiple hypotheses and consider outcomes probabilistically, even in the face of what to most people would appear to be rock solid data. Makes us almost as frustrating to deal with as lawyers.

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Permalink Reply by Bad Finger (Eric) on April 10, 2012 at 6:27am

If it is a uke with nylon strings then the tension should be fairly low compared with a steel string guitar.  Could be worth a try.

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