I am a bone artist and collector, and honestly I love everything about the actual collection and cleaning of bones. It's both much easier and much more complicated than folks tend to think. If you're squeamish I understand if you don't read on, however.
I'm a small artist (my art tumblr is boundless-ennui, if ever you're curious as to what I make - I don't know how to change which tumblr does an ask) but part of that is sourcing my own materials. I can't stand the idea of an animal being killed just so I can have its bones (a lucrative trade) and so my wife taught me how to process bones myself.
I hate animals dying. I know it happens, it must happen, but I hate it all the same. But when a hunter kills an animal and takes it to a taxidermist or a trapper is paid to kill animals nothing I can do will stop it happening, so instead I try to make the death go a little farther, if that makes sense. I work with farmers, trappers, taxidermists, and anyone else I can think of who might be in the way of having carcasses they don't want to keep. I've got a farmer right now who keeps me apprised of the dead sheep in her "death pit" so I can come out and get the skulls when I've time.
Processing bones is a thing unto itself. First I have to get all the flesh off, and the "safest" (for a given value of safe) is to macerate, or rot in water. Basically I put the carcass in a container full of water, put a lid on it, and wait. This can take anywhere from months during the hotter seasons to over a year if I start it during cold weather. My wife finds this hilarious as I am by nature an incredibly impatient person who is dedicated to a hobby that can take upwards of a year just for the first step to properly complete.
There are other methods and many of those depend on what space you have. A few other methods are such as dermestid beetles,the most efficient method, but they need specific temperatures and can die off if you're not paying attention, and anywhere they are will always smell faintly of rot. There are carcass cages, which is where you put a carcass in an open air cage for bugs to do their work but that is a very bad idea if you have neighbors within smelling distance. I live in a city so I macerate, which somewhat contains the smell. There are also people who swear by boiling but by and large the bone collecting community is against it - if you do it wrong (it's very hard to do right) you boil the fats into the bones and destroy the bone's integrity so they will only last a handful of years instead of decades.
With maceration once the flesh has rotted off (and you learn to tell when that is) I pull the bones and begin degreasing/whitening. Degreasing is just the bones in water with a degreasing agent, usually Dawn dish soap. When the water gets cloudy that's fats being pulled out of the bones, at which point I pour that water off and add more of the same until the water stays clear or clear enough for me.
Whitening is _not_ bleaching. Bleach destroys bones. It's either hydrogen peroxide (the bottles you get at Costco and such - if it's concentrated then it needs diluting) or water and hydrogen peroxide. The hydrogen peroxide eats up anything organic that's left in the bones, brightening the color. I pull them periodically and let them dry to see if I'm satisfied with the color, and if not then the bones go back to either degrease or whiten more. I've had some bones that have been in processing for over a year. I refuse to sell greasy bones.
The reason this matters is because fats in the bones can start to rot again over time. The yellow you see in certain bones (once you know what to look for it's incredibly easy to spot) is fat. It can start to smell or attract bugs. Bones worn as jewelry can also absorb oils from skin so now I seal all my bones before I put them into jewelry pieces that will touch skin, such as necklaces.
With all this in mind you can see why I have to stay small. How I source bones means many times skulls don't have all their teeth, which is something folks often want and can always get with farmed animal bones. My bones often have damage from either cause of death (being shot, being hit by cars, an unfortunate farm incident that led to bones that had been savaged by a neighbor's dogs) or I don't have the size they'd prefer or the volume wanted. I don't charge as much as I should considering how long the process takes but I still charge more than folks that farm bones because I have to put in a lot more legwork to find mine, let alone process them.
On the bone collecting subreddits (there are several depending on key words/focus of interest) folks will often post skulls or animal tails they bought at a con or oddity shop and ask if it's ethically sourced. Disregarding the fact that there is no "ethical" sourcing (there's no agreed upon definition of the term, i.e. I consider it ethical if _I_ didn't kill the animal myself, so my friend killing it for me is ethical) if you see a table with, say, ten fox skulls that are all roughly the same size and quality then that person did not source them outside a fur farm - those animals were all raised to the same age/size and killed at the same time; if you see a table laid out with huge fluffy tails in a variety of colors then those animals were all killed specifically for that tail. You can't hope to find ten animals of all the same size/life experience through any other method, nor reliably source perfectly fluffy tails without hunting animals specifically for that or getting them all from a place that breeds for that trait. By the time I find a carcass most of the time the fur is already slipping off - it's a big problem for folks wanting to learn taxidermy. Preserving tails at that stage is a complete gamble, so a table full of them isn't sourced that way.
People will also post bats, either skeletons or taxidermied or preserved in resin, and ask if those are ethical. They never are. Bats are a protected species in many, many countries and where they're not they're incredibly hard to find already dead. They're small and light and an easy snack for whatever finds them first - finding them dead and intact is purest chance. Unless you get a bat from a person you specifically know who you _know_ only does sustainable collecting (the actual term usually used, folks in the know don't say ethical) then that bat was almost definitely captured in a net alongside many other bats and killed specifically for that art piece. This mass killing is a huge problem and is devastating many bat populations.
And while I'm ranting (this is me enjoying myself thoroughly - I don't get to talk about all this in detail very often) teeth are another big one. I have entire bags of assorted teeth because as said with maceration teeth come loose or the skulls themselves are already missing teeth when I get them. I don't like the gaps so I pull teeth if a skull doesn't have all of them or replace the teeth with things like stone chips and suchlike, depending on the piece. I have two dog skulls right now where if I want "fangs" then I'd need to pull the teeth from those skulls, leaving them without those teeth. I only get four per carnivore so I have to be careful which I use for what. In order to have a bag of twenty or forty or more of these specific teeth I would have to be mass killing and pulling these teeth from that many animals. That being said you can easily find bags of that many and more of those specific teeth on various sites, especially Etsy.
Thank you for coming to my TED talk.
You know I tried to find a gif that would be a representation of me staring at you in open-mouthed fascination. I was unsuccessful so you will have to imagine the open-mouthed fascination please.
First: thank you. Never in my wildest dreams would I have predicted receiving this ask when I made my post and as someone who adores learning new and obscure facts I am extremely pleased.
Second: I will admit that on reading your first sentence I thought this might be the return of the tumblr bone-stealing witch and was relieved that this was not the case. Sustainable animal bone sourcing > grave robbing.
Third: Wow… just wow. This was not a thing that I knew anything at all about and I am very glad that I do now.
Fourth: How do you dispose of the water you use for macerating and the stuff that is in it at the end of the process? And I guess also what I imagine to be a whole lot of hydrogen peroxide?
Fifth: Do you ever mix and match teeth? Like oh these look approximately goatish I will add them to the goat skull so there are no gaps? Or do you do things just with teeth?
Sixth: Have you ever gotten a really weird bone?
Thank you, again. I saw this ask come in last night and read it a few times and decided I needed the benefit of a full night’s sleep before responding. Fascinating!