On mammoth and other porous ivories, sand by hand to a very fine grit (at least 1000). Seal the entire handle with thin CA (cheap dollar store super glue will work, but super-thin CA is better).Let it soak in and cure (don't use accelerator) for 24 hours. Repeat as many times as is necessary to get to a point where no glue will absorb anymore. It will look terrible, but that is OK. Use acetone to get any dried resin off the metal parts, then hand sand the excess off the handle, starting with 400 grit. Go to as fine a finish as you have available.
I like the 3M sanding sheets . The cloth like sheets are color coded and go up to 8000 grit. Often, using these sheets, you will not need to go to the buffer at all.
If you do need to buff it, tape off all metal and buff gently. It won't take much to make it shine . Less than a minute should do it.If it takes longer, then you haven't sanded the ivory smooth enough yet.
Hand buffing with a charged cloth is another good way to avoid burning in polishing stains. Tape off the metal, take a soft cotton cloth and rub it with some white or pink polish. You don't need it caked on the cloth. Hand rub and buff the handle. Continue to charge and buff until the shine is bright. (BTW The bolster/guard can be hand polished the same way....just tape off the handle to avoid metal stains. A commercial metal polishing cloth will usually work fine for the metal.).
The handle and blade can be cleaned with denatured alcohol after buffing ,to remove any residue. I don't recommend using acetone unless it is absolutely necessary, because it will remove some of the CA resin from the handle ,and may dull the shine a bit.If you do need to use acetone, use it quickly, and wipe off the extra immediately. A light hand buffing will usually restore the luster.
This technique is not intended to coat the ivory, but to seal it. It will leave a beautiful shine and greatly prevent the ivory taking in dirt, polish, and other stains. It also helps prevent later cracking.
Stacy