Years back, when by father started making and repairing guitars, he was too thrifty (i.e. cheap) to pay the high price of quality bleached bone nuts and saddles. After all, he bought all his own lumber to resaw for tops, backs and sides, he found flitches of aged spruce and hand split his own braces. So why not make the bone nuts and saddles as well?
When he first approached me with his latest idea, I said you wanna do what??? Are you sure you want to do this? That borders on the slightly gross category I thought. But, as he typically did, he pursued it and he produced beautiful results. After I thought about it, it was not worse than mom cleaning the chicken or turkey for dinner.
Obtaining Bone Stock:
The best place to look good quality bone is in your local grocery store. Buy a fresh cow “knuckle” or a section of long bone, the type commonly sold for soup and not always on display but almost always available. You can also use other long bones and the bones of other mammalian species, but cow bone has the virtues of density, size, and limited (sometimes nonexistent) marrow cavity. If you want to cut down on your work load ask the butcher to trim away the knobby ends of the bone.
Once you arrive at your shop, try to extract as much soft tissue as possible from the exposed marrow cavity .
Boil The Bone To Remove Remaining Soft Tissue:
Next it is time to boil the bone to remove the remaining soft tissue. It is best to use water mixed with detergent on the stovetop. You can also use water mixed with household ammonia on the stovetop, which is quicker or pure water, which takes longer. Bring the liquid to a boil, then reduce heat and simmer for 30-40 minutes (ammonia in water), 50-90 minutes (detergent in water), or up to two hours (pure water). The objectives are to cook away the soft tissue and to begin the degreasing process. Be sure to turn on the exhaust fan during this process.
After the appropriate boiling time, remove and cool the bone, then use running water in combination with fingernails and a stiff brush to remove the remaining soft tissue. Don’t be afraid to return the bone to stovetop to repeat the process.
After the bone is cleaned of soft tissue, let the bone air-dry for a day or so, then using a bandsaw or hacksaw cut the large bones into oversize blanks (bridge, nut, saddles, etc). Air-dry the blanks for at least a week. More time is better.
Degreasing Is The Most Important Step:
At this time the bone needs to be degreased, as the bone harbors a lot of oils. These oils tend to migrate out of the bone over time and this grease does not mix with glue joints very well, and it can migrate into the wood and cause major problems for a bridge or neck. Degreasing is the most overlooked, under-done, but one of the most important steps in bone preparation.
To degrease bone, immerse the very dry blanks in about ten volumes of white gas for 1-3 weeks. White gas, such as Coleman fuel, is extremely flammable and so this step should be done in a glass container outdoors somewhere in the shade far from structures (even though Coleman fuel is supplied in a metal can, a small volume can be safely stored in a glass jar or bottle with a tight-fitting leakproof lid). Greasy bone will discolor the white gas after just a day or two so replace it at that time. Talk to your local fire marshal about legal methods for white gas storage and disposal.
The degrease time can and should be extended if the bone shows any sign of grease, such as translucent spots on the surface of the bone. When the bone is degreased, remove the bone blanks from the gasoline, rinse once in clean gas, and air-dry.
Degreased bone should dry quickly, typically in an hour or less. If the blanks dry slowly, there is residual grease in the bone so return them to the (new) gasoline bath. Just be sure all traces of the grease are gone before you use the bone in a wood instrument.
Dry & Shape The Bone:
Next, shape the bone and final-fit, smooth with a mill file, sand with 320, 400, and 600 grit wet or dry paper each used dry and then wet with water, and finally buff with tripoli, then rouge. After all this the bone will be shiny and yellowish-white in color.
The last step is the final whitening step, which will give you a bright white appearance of commercial nuts and saddles. Bleach the bone by immersing for 10 minutes in 3% hydrogen peroxide, available from the drug store, in a glass jar without a lid. Do not over-whiten as longer immersion tends to over-whiten and makes the bone look flat. Air-dry the bone and glue or set in place.
If the bone is relatively level, it will remain in place during the pass through the sander. Continue to do this until your optimum thickness is achieved. Do the same with a jig for the bone nuts.
Next take the bone to the Belt sander and square them up on a course belt. Then switch over to a fine belt and touch them up and final size them. It really works well yo use the Belt Sanding Fence for this operation. If you find that the final shaping gets you into some discoloration again, feel free to dump these pieces back in the bleach solution and whiten them up.
As you can see, there are a lot of steps to achieve the best results for great, whiten bone of great quality for a handmade instrument. Quality bone from many suppliers in bulk is hard to beat, but if you are willing to go through the process, as my father was, you can make bone nuts and saddles in bulk with great results and save some $$$.