I can't find hardness numbers on Lignum Vitae, but it's density is widely reported as 1.09 g/cc; compare to 2.06 for cow femur and 2.69 for aluminum.
Yes on density/porosity working against each other, but I think that conflict is in our favor. Here are my major data points, crudely summarized:
- Dense, soft materials like lead don't conduct/transmit vibrations well at all.
- Dense, hard materials conduct vibrations very well.
- Dense, hard materials (e.g., brass) are widely reported to sound too bright. Theory: they conduct high/fast vibrations too well.
- Bone is dense and hard, thought not nearly as much so as the metals, but doesn't sound too bright.
- A ceramic saddle is more dense and hard than brass, yet doesn't sound too bright.
That leads to the key question: what do bone and ceramics have in common that isn't
density or hardness, to make them both sound better?
My theory: their porosity. I'm thinking that the voids are damping the higher vibrations, resulting in a sound more in tune with the natural vibrations of the wood top, thus sounding more natural to our ears. There are several powdered materials than can be added to resin which bring characteristics of both porosity and additional hardness; powdered ceramics or calcium carbonate are examples. My hope is to find a mix that makes a suitable replacement for bone, yet is easily cast for faster production.
If that theory is correct, it might be that true ivory actually does sound better than bone - because the voids in ivory are much smaller and more organized than the voids in bone, resulting in more consistent damping and the silkier tone.
My starting place for materials data is http://www.matweb.com
. There are several other materials databases out there, but that one is most extensive.
One more time: this isn't my field of expertise. I'm just a sucker for a challenge.