Bone Sources: The butcher. Really. My wife buys stew/dog bones are the grocery store for $2. 4"-8" long. There's a real butcher near me, I'm going to go down and talk to them soon and see if I can get bigger bones. Pet stores have bone too, but you don't know how they prepped it. Look for white, clean bones - not the smoked/barbecued bones.
Meat & Tendon Removal: This can happen lots of ways.
- I use the dog, mostly. Give her the bone for a week or two and she strips it clean. Then I trade her a new fresh bone for the cleaned one.
- You can simmer them in water for a few hours and then scrape. I have heard warnings not to boil them or you will do bad things to the grease. Just simmer. You can add some ammonia or detergent to help the process (I have not tried this, but seems fastest.)
- Put them in a bucket of water & cover. Change the water once a week. Apparently it takes quite a while (couple months) but is the easiest & least damaging to the bone (I have not tried this).
- Corpse beetles. Yuck and too much work. I didn't bother investigating this option.
Degreasing: This is the tricky part, and I've read lots of opinions. This article for luthiers is very good, but might be overkill for knife handles. But it really comes down to using some kind of solvent to remove the grease unless you have a long timeline for your prep. Here's my solvent summary:
- Bleach - don't use it. While it is effective at removing grease & whitening it will break down the bone over the years. Nothing like having the knife handle crumble to dust in a decade to piss off a customer.
- Detergents (Simple Green, Dawn, etc) - these seem to work, but take time. I've been using Simple Green in water. I changed the mix once a week and soaked for 6-8 weeks. Slow but easy. Also fits in well with dog-cleaning method.
- Coleman fuel (white gas): It was recommended by a number of people. No downsides I have heard of except it's explosive nature. Soak times I've heard ranged from a day to 3 weeks.
- Acetone. Not a lot of data available, other than people saying it works. Downsides are nasty fumes and it's expensive. **I have tried this a number of times now and it is my preferred methods. I put the bone in a big mason jar full of acetone. The acetone lasts over a number of bones, and the bones come out clean and don't stink like they do with kerosine.
- Kerosene. This paper says it works as well as acetone and is one tenth the price. It's the same idea as Coleman Fuel. Light-weight petroleum distillates will dissolve grease into themselves and then evaporate quickly out of the bones. **I have tried this method since I posted this. It works and kerosine is cheaper than acetone, but the bone stinks of kerosine for a long time afterwards.
It also seems that putting the bone out in the sun or heating it gently will reveal the presence of grease. The heated grease flows and stains the bone.
As a knife maker I think that the main factor that will determine how anal you are about preparing bone is how you are going to affix it. If you are going to rivet scales onto a full tang handle, relying on epoxy only for gap filling, I'd say you don't have to be too fussy. Making a bone inlay that will be glued into a wooden handle? Get fussy ala the luthier article.
The bottom line for me is the some words of wisdom I heard Rick Furrer utter in relation to making your own steel "Don't make what you can buy." Unfortunately I haven't a source for nice, thick, professionally degreased bone for carving. Yet.
