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.
Nice! I'd like to add that sheep bones are the strongest commercially available. They are documented in their use in crossbow bolt points in Poland (15th or 16th century, I forget). They are a bitch to carve for that reason. I was instructed to soak the bone until it's soft and almost elastic and carve it then - the problem is germs. People use bleach or vinegar to suppress germ growth and smells, but as you said bleach will break the bone down, and both will make the bone smell for a LONG time. Does the detergent eliminate the germ/smell issue?
ReplyDeleteMy guess is that the smell comes from a combo of the bones being soaked in water and not fully degreased. That gives bacteria something to grow on. I don't know if detergent will retard bacteria growth. I'd try soaking them in water with some ammonia (5%?) in a closed container. Ammonia stinks for only a short time, and nothing grows in it. Hopefully the ammonia will evaporate in the first hour out of the soak.
ReplyDeleteI should say all the 'carving' I have done or plan to do will be done with files & rotary tools on dry bone, so I have no clue about carving it wet with blades. I know people do that with antler - time for more research!
Another thought: Go through the process I described for dry bone carving, including a week in kerosene/acetone/white gas. That should kill everything in the bone. Then soak in a covered container with distilled water until soft. The idea is to kill all the bacteria and then not introduce any new ones during the soak.
ReplyDeleteMore experiment results: I soaked some bone in kerosene for 3 weeks. It probably removed the grease, but the bone stank of kerosene for 2 weeks afterwards, at which point I heated the bone to 200 in the oven to try and drive off the remaining kerosene. That simply caused to bone to crack. Lesson learned: Don't use kerosene for degreasing. I'm back to acetone. I'll try coleman fuel when I find some.
ReplyDeleteI'm getting ready to prepare some bone and antler for needles, beads and other bits for my SCA persona. Since I'm living in a small apartment, the dog-and-detergent process seems the most effective way to do the job and avoid problems with fire and disposing of smelly and toxic waste. Thanks for posting comparisons of the various methods!
ReplyDelete