#animal processing

First, go down a little list to figure out what could be causing the smell you’re dealing with. 

1. Is the skull fully clean?

-If not, then this is why your skull stinks. Any leftover rotting flesh or viscera will be not only a source of smell, but it can attract bugs, bacteria, and even start growing mold. Toss that critter back into maceration and let the rest rot off, unless you’re willing to pick it all off by hand. (No shame! I’ve done that plenty of times) 

2. Does the skull need degreasing?

-A greasy skull can definitely be a stinky skull. Make sure you thoroughly degrease your skull, and the smell should go away.

3. Is the skull waxy?

-That's grave wax, baby! Adipocere doesn’t usually smell, but sometimes it can really pack a nasal punch. You can remove it by scraping it off with a toothpick, an X-Acto blade, whatever you’ve got around. Even better is an old toothbrush; Brush away dry or under running water, it’ll come off relatively easy. Go ahead and use some dish soap as well, that’ll help give the skull a better smell.

4. Where is the smell coming from?

-This is probably the first question you ask yourself; Why does my skull stink? And Where is the stink coming from? Built up smell likes to linger in spots where the bone is dense, or where there’s a lot of small places for tissue to hide. The brain cavity can smell a lot like cat piss, in my personal experience. Brain likes to get really nasty while it rots. That’s one of the toughest smells I’ve had to get out of a skull, it’s just such a lingering scent. Smell coming from the nasal cavity could very well mean that there’s still tissue shoved up in there that needs to be fished out or rotted away. Locating the source will ultimately help you figure out what you’ve gotta do to remedy it.

5. Any weird discoloration?

-While not every bit of discoloration will smell, if you’re having a hard time finding the source of a smell, sniff the discolored spots. They would be stains from tissue or bacteria that occurred during the cleaning process, or could be hidden pockets of grease. 

6. Is the skull fully dry?

-Sometimes it can be hard to tell if a skull is all the way dry. The surface may be, but depending on how dense the skull is, water could take longer to dry out. If its degrease water, peroxide, or maceration water, it can smell. They may be cleaning process, but they can really smell bad. I personally have a degrease bucket that I haven’t messed with in a few weeks, affectionately nicknamed “Fart Bucket” because it smells horrible.

Now that that’s out of the way, let's get to the options you’ve got. There’s a few different things you can do, varying in involvement, chemicals, cleaning agents, and time.

Peroxide

A good starting place would be to give the skull a soak in warm water and peroxide. It can knock loose random dirt, and will begin to oxidize and puff up any remaining tissue. That’ll make it easier to spot and pick off if that’s what you feel inclined to do. You can leave the skull to soak for as little or as long as you want, though of course peroxide will begin to whiten the bone. If that’s not the desired effect, limit the soak to around 15-20 minutes. Give the skull a good thorough rinse afterwards to flush out anything that was knocked loose or that you decided to remove, and let it dry. If there’s persisting smell after that, move on to a different method! Peroxide will help with the little smells, but a bigger smell will need a stronger approach.

Heavy Duty Scrubbin’

Grab a bucket, some hot water, a scrubbing brush (Hard bristled toothbrushes are amazing for this) and your favorite smelling, strong dish soap. Lather up your skull and get to scrubbing! Don’t be shy with the soap, make sure you’re thorough. Scrub inside the nasal cavity (Carefully, if the turbinates are still in there), inside the brain cavity, around the sockets of the teeth, etc.. Rinse the skull off every once in a while and start again. It’s tedious for sure, but the results are what you’re after. 

The lower jaw will be an interesting clean job. The hole that runs through the mandible (Mandibular Foramen) can contain a lot of excess grease, build up, or left over meat. If you have em’, grab a couple of pipe cleaners and run them through that hole. Pour some soap into the hole, and keep flossing the pipe cleaner through.It’ll break the excess loose and clear it out on the way through. Make sure you have a few on hand, they’re likely to get really gross really fast.

Let your skull dry and give it a sniff. Still stinks a little? Try again! There’s no harm in scrubbing; Do it until you reach your desired result, or try something new. Either way, no harm done.

Soaks

If you want a less involved method, you’ll probably want to try soaking skulls in a couple of different mixtures. I excluded peroxide and made it its own category because of the chemicals bone whitening ability. It’s not a prolonged soak kind of thing, but these are! These soaks will also act as degreasing baths, given what you use.

Ammonia Soak

-Get yourself some lemon scented ammonia from the dollar store or wherever you may find it. (It doesn't have to be lemon scented, but citrus is an odor killer). Fill up a bucket with enough hot water to cover most of the skull, and then fill up the rest(about an inch or so over the skull) with the ammonia. Ammonia on its own isn’t a necessarily pleasant smell, but it’ll be diluted by the water and won’t ultimately smell like ammonia once dried. You can let this soak for however long you please, but if you’re in a hurry just wait until the water is cold and pull it out. Let it dry, and check it out. The longer you let it sit, the more likely the smell will dissipate. If you have one, a tank heater will keep the water warm and help the ammonia work it’s way through the bone and pull any residual grease out; Grease very well could be the source of the smell.

Acetone Soak

-You’re gonna do pretty much the same thing with this soak as you do with the ammonia, the biggest difference is that you’re only going to use a few ounces of acetone. It’s a strong chemical that works just fine in small quantities. Make sure the water covers the skull completely and then some, and then pour in around half a bottle of acetone (Standard bottle of nail polish remover) depending on the size of your container. Let it soak until its cold, or keep it in until you feel like taking it out. Acetone has a strong smell to it, and is also an agent used for degreasing. You’ll be looking at a two for one like with ammonia. If the smell persists, give it some more time. 

Dish Soap Soak

-Like the last two; Bucket and hot water, fill up above the skull, and then squeeze in some dish soap. Whatever smell you like, use that. Stir the solution up so it’s nicely mixed, and let it soak until its cold or longer if you wish. Let the skull dry, give it a sniff. The longer it hangs out in the soak, the more likely the smell will go. 

With soaks, you’re going to want to check the solution if you leave it sit for a long period of time. If it begins to smell nasty or get cloudy but you aren’t ready to pull it out yet, go ahead and restart your soak solution. The only thing worse than the smell leftover from bone cleaning processes, is the mixture between that smell and dirty degrease/soaking solutions. It’s like getting punched in both nostrils simultaneously. 

Obvious but mediocre solutions

(These are things my taxidermist friend has told me about clients doing in the past, and some are from personal experience. Some are good, some are just...not.)

-Spray em down with air freshener! It’ll help for a very short while before it wears off and goes back to smelling.

-Stick some dryer sheets in the back of the skull, why not

-Rub em down in coffee grounds (This can stain the bone)

-Stick em in a bag of coffee beans (This could also stain the bone)

-Sprinkle them with cinnamon (I have had this stain bone and it’s also like you’re just asking to get cinnamon in your nose)

-Soak them in rose petal water (Can’t speak to this method)

-Set it out in the sun for a few days, let the heat leech out the smell (This can bleach the bone if you leave it too long.)

Realistically, you can do whatever you need to do to get the job done. Just make sure you aren’t using agents that will damage the bones (or yourself) and you’re good to go! Keep in mind that bones that are already brittle, such as nature cleaned, sun bleached, boiled, or bleached skulls can be damaged by some of these processes. If they are brittle to the touch, flaky, easily scratch-able (As in you can put a scratch/groove in the bone very easily), or seem all around unstable, use your best judgement to decide whether or not you should clean them at all. Sometimes weird smelling skulls just need to be put in a display case or somewhere out of smelling distance and left alone.

These methods are applicable to all bones, not just skulls! But as i said above, use your best judgement to determine if the bone will hold up to any of these processes.