My strange and wonderful daughter has an obsession with bones since she was 3. She even asked me if she could have my bones when I die. I said yes, but since we aren’t at that point yet, right now we are gathering all sorts of animal bones and cleaning them. 🙂
There is a lot of info on the web about how to clean animal bones — but a lot of it is inaccurate or impractical. Before you dive into this, here’s the gist of what you need to know:
- Never use bleach to clean bones. It will destroy their structural integrity.
- If the bones still have tissue on them, soak them. Don’t boil them as it will trap fat in the bones and make a nasty mess. You can also use insects to remove flesh but they will leave some tissue behind
- Bones contain a lot of oil and must be “degreased.” This is actually one of the most confusing and frustrating steps of cleaning animal bones!
- Hydrogen peroxide is the best method for whitening bones. Hair developer is the same thing as hydrogen peroxide.
First I’ll talk about how to clean bones with just hydrogen peroxide. Then, I’ll tell you a good hack using baking soda to clean very large bones.
- Which Hydrogen Peroxide to Use?
- How to Clean Bones with Hydrogen Peroxide
- The Baking Soda Method (for Large Bones)
Which Hydrogen Peroxide to Use to Clean Bones?
Hydrogen peroxide (H2o2) is the best thing for cleaning and whitening bones. Unlike bleach, it won’t destroy the bone’s structural integrity. This is what taxidermists use, including the ones at the Smithsonian and other prestigious institutions.
Here’s the problem: The hydrogen peroxide that you buy in drug stores is usually just 2% concentration. This H202 will work for whitening bones. However, you’ll have to buy a zillion bottles of it. Since it is so weak, you’ll probably need to do numerous soaks until the bones actually get clean and white.
To save yourself time and money, ask your pharmacy for 20% hydrogen peroxide.
Unfortunately, not many pharmacies stock hydrogen peroxide in that concentration. Sometimes, you’ll have to provide your ID in order to buy 20% hydrogen peroxide!
I was only able to find 20% H202 because I had a hookup in one pharmacy. She special ordered it for me. It pays to have connections!
Can’t Find 20% Hydrogen Peroxide?
If you can’t find 20% or higher hydrogen peroxide, you can use hair developer. I’ve since lost my pharmacy connection, so now only use hair developer for cleaning bones.
There are two types of hair developer:
- Clear Developer: This is the exact same thing as the hydrogen peroxide you’d get in a pharmacy. It will bubble up nicely and works great for cleaning bones. Get 40 volume clear developer here.
- Cream Developer: This has some emulsifiers added so it is creamy and thick. Some hardcore taxidermists won’t use it, saying the emulsifiers could mess up the bones. It also won’t bubble up like clear H202, so it isn’t as good at getting stains out from deep within bones. However, because cream developer is thick, it can be painted directly onto bones. That makes it great for spot whitening, or for whitening skulls with horns. You can just paint it on around the horns. It does dry quickly though, so you’ll need to cover the bones with some plastic wrap. Get 40 volume cream developer here.
Hair Developer Strengths:
Hair developer is listed in strengths by volume. Don’t think that 10v equals 10% though. The actual concentrations are as follows:
- 10 volume =3% hydrogen peroxide. Don’t get this. It’s too weak for good results!
- 20 volume =6% hydrogen peroxide.
- 30 volume =9% hydrogen peroxide.
- 40 volume =12% hydrogen peroxide. Not quite 20%, but it will still do a great job!
You can buy 12% hydrogen hair developer (40v) on Amazon here. It’s the cheapest I’ve found and the strongest hydrogen peroxide you’ll likely find unless you happen to have a hookup at a pharmacy.
Cleaning Bones with Just Hydrogen Peroxide
Cleaning small bones is pretty easy. However, it may take some time -especially if the animal is fresh and has lots of soft tissue on it still.
- A bucket or Tupperware slightly bigger than the bones you want to clean
- A lid for the bucket (or improvise one out of a plastic bag)
- Dish soap
- Old toothbrush
- 20% (or higher) hydrogen peroxide
- Water for diluting
- Rubber gloves – absolutely necessary! Hydrogen peroxide will turn your fingers white.
- An outdoor space – hydrogen peroxide stinks and you really shouldn’t breathe hydrogen peroxide vapors in.
Step 1: Remove soft tissue
Method 1: Maceration (Soaking)
If your bones have soft tissue or rotting flesh on them, the best way to remove is it is with maceration. Basically, you put the bones in water and let them sit so natural bacteria can remove the tissue– potentially for MONTHS. Because I live in a small apartment without a yard, I’ve only done this with small bones. At one point, I had 3 jars with dead animals soaking under our bathroom sink! 😮
Method 2: Burying
Alternatively, you can bury the bones. Bacteria will eat away at the bones (and maybe some worms/bugs will eat it too). But this also takes a long time. I get grossed out easily, so I won’t dig up any bones before 2-3 months. I’d probably puke if I saw rotting brains leaking out. :/
We found this intact dead bat while camping. I wrapped it in cheesecloth (to make finding the small bones easier) and put it in a Tupperware container filled with dirt. The container is hanging out of my apartment window! I poked some tiny holes in the top/bottom of the container because it seems like a bit of rain will make the microbes happy. No scientific evidence to back that up though.
Method 3: Soaking in Biological Powder
The fastest method for removing soft tissue from bones is to use biological cleaning powders/enzyme stain removing powder such as Biotex (which you can buy here) These cleaners contain enzymes which will break down the soft tissue. Just soak the bones in a solution of the powder + water until the tissue becomes soft enough to scrape off.
Yes, the soaking bones will stink. Yes, you’ll have to dump the water frequently until the bones actually get clean. It will be frustrating and gross.
Method 4: Boiling (NOT RECOMMENDED!)
Boiling bones will loosen soft tissue and cause it to fall off very quickly. However, boiling will cause fat to get trapped inside the bones and they’ll get all white and shiny looking.
If you are impatient, you can boil bones. Just try to remove as much of the hide and hair as possible. These have a lot of oils in them which will soak into the bones when boiling. You’ll then end up with gross yellow spots that are difficult to remove.
While boiling is a no-no for cleaning bones, steaming should be okay. The steam will loosen tissue quickly. Since the bones aren’t floating in tissue-filled hot water, the fat won’t absorb into the bones. While I haven’t tried this personally, but Jake of Jake’s Bones uses a baby bottle sterilizer for cleaning tissue from bones. Basically you steam the bones inside the sterilizer. He warns that it will smell disgusting!
Removing Brains from Skulls:
I’ve only done this once. It was gross. Really gross. What’s worse is that I didn’t know there were still brains in the skull!
A year ago, some nice guys from the local vet college gave my daughter a pig’s skull (see picture above). They’d boiled it to remove the tissue. I didn’t think to ask them if they’d removed the brains.
I decided to see if I could get the skull to look nicer by soaking it in soapy water (to remove the fat trapped inside). Yep, lots of fat came out. So did pieces of brain!
Here’s what the guys should have done:
- Soak the skull to get the brain tissue soft (or give the skull a quick boil if you aren’t too worried about it turning yellow)
- Take a wire/coat hanger and start jamming it into the skull. The goal is to “scramble” the brains. This is something the ancient Egyptians mastered thousands of years ago. 😉
- Get a power washer and blast into the back of the skull. Brains will shoot out of the nose. WEAR GOGGLES unless you don’t mind getting pieces of brain in your eyes.
- Or use a saw to cut off part of the back of the skull and scoop out the brains. Some skulls (like deer skulls) sit better on their mount when the back is flat anyway.
It’s interesting to know that the skull sat in my daughter’s room for over a year with brain tissue inside. It didn’t stink at all. I’ve managed to whiten the boiled skull. I’ll update with pictures later.
Be warned that there is a lot of tissue hiding in animal skulls – especially big animals. For example, there are often giant nerve endings inside teeth. You will also have nerves going through foramina in skulls.
To remove this tissue, you may need to:
- Carefully remove teeth with pliers. Wash/poke out nerve endings. Make sure to reinsert the teeth while the skull is still wet. Otherwise the bone shrinkage might make it impossible to get teeth back in.
- Use wire to poke tissue out of foramina: This is hard to do. One more reason to bury bones for cleaning off tissue. Bacteria can get into those tiny holes and remove it. Soaking bones or leaving them to bugs won’t get this tissue.
Step 2: Pre-clean the bones
This applies to bones you have found which do not have any soft tissue on them, but are caked with dirt and maybe have moss growing on them.
Use soapy water and the toothbrush to SCRUB the bones clean. The cleaner they are when you start, the better the hydrogen peroxide will work.
Step 3: Soak the Bones in Dish Soap (Degreasing)
Bones actually have a lot of fatty oils inside of them. If you try to clean them with hydrogen peroxide before removing this oil, you’ll see it float to the top of the brine. Gross!
So soak the bones in soapy water for at least 12 hours. Dawn dish soap works great. If they are really gross, then you’ll need to dump the water and re-soak.
Don’t skip this step. It is really important for getting good results. If you don’t get all the fat out, the fat will eventually cause the bones to rot (yes, ROT) and turn yellow. For really greasy animals, the bones might start to stink too.
Notes about degreasing:
- Some animals (like possums, bears, boars, and pigs) have insane amounts of fat in their bones. You’ll have to degrease them for a LONG time.
- See yellow spots on the bones after whitening? This is from fat. You’ll have to degrease them again.
- HOT water works best for degreasing. Some people use aquarium heaters to keep the water hot during degreasing.
Step 4: Now Soak in Hydrogen Peroxide
Put the bones in your bucket. Pour in your hydrogen peroxide. Then top it with water. The bones will start foaming, which means the hydrogen peroxide is working. Hydrogen peroxide also heats up when it is working.
How much hydrogen to water? The higher the concentration of hydrogen, the faster and whiter your bones will be. Unfortunately, that can mean spending a lot of money on hydrogen peroxide. That is why it is so important to find a container which fits your bones exactly. The less excess space around your bones, the less hydrogen peroxide you will have to use.
For my small bones, I used a ½ liter of 20% hydrogen peroxide plus about 1 1/2 liters of water. They came out clean in 1 day.
Remember that hair developer works just the same as hydrogen peroxide. It just won’t make as much bubbles and is a lot cheaper. You can buy it in bulk here.
Tip: Cover the bones while they soak. The H202 will stay active longer this way.
Step 5: Cover and Leave for 24+ Hours
It is important that you cover the bones once they are in the hydrogen peroxide solution. The lid will keep the fumes within the bucket and help it work better.
Check out the before/after of the cat skull below. This was after one round of soaking in 40volume (12% hydrogen peroxide) hair developer. If you want your bones to be realllly white, then you’ll have to do several rounds — especially if they were super dirty like this cat skull was (it was half buried in dirt when we found it).
*Note about Cleaning Very Dirty Bones
Isabel found an extremely dirty cow hip bone that was sitting in a river for god knows how long. It had all sorts of river scum on it. I precleaned it as best as I could with soapy water.
Then, because I couldn’t find a bucket to fit it, I used a method that I’d tried with other bones: I put the bone and hydrogen peroxide + water in a plastic bag. Tie and let soak.
Well, the hydrogen peroxide went crazy on the dirty bone! It started steaming and got HOT. I thought it was going to melt the plastic bag!!! You can see in the picture all of the steam coming off the bone.
Eventually I used a plastic drawer tilted on its side to soak the bone in. The hydrogen didn’t go as crazy on the second round, but still bubbled a lot. The bone came out nice and clean. At least cleaner than how we found it. 🙂
Using Baking Soda + Hydrogen Peroxide for Cleaning Very Large Bones
Isabel’s friend found a cow’s skull for her (what other 6 year old is lucky enough to have a friend who saves bones for her?). The skull was free of soft tissue, but was still really dirty and stunk badly. I didn’t realize it smelled so badly until halfway home on the bus. Sorry to all the people who had to put up with the rotting smell on the 30 minute bus ride! 😮
Cleaning such a large bone presented some problems:
- I literally could not find a plastic container large enough for soaking the skull. Not even laundry baskets were wide enough to fit it.
- I would have had to use TONS of hydrogen to immerse the bone. I’m not a rich person and wasn’t thrilled about spending $50+ on peroxide for a skull.
My first (unsuccessful) solution: Soak the skull in a doubled trash bag
I put the skull into a big trash bag, poured in some hydrogen and water, and then tied off the bag. I kind of propped everything up in a plastic drawer.
The hydrogen peroxide did whiten the skull a bit, but of course the trash bag sprung a leak. The peroxide pooled at the bottom, so only part of the skull got whitened. You can see a line on the skull from the part which was sitting in the most hydrogen solution. It looks terrible!
A better solution: Mix the hydrogen peroxide with baking soda
Baking soda is a natural cleaning agent, right? Could I mix it with hydrogen peroxide to form a paste, and then spread the paste on the bone?
I did a small test batch. The baking soda and hydrogen foamed a bit when mixed up, but still formed a paste that could be spread onto the skull.
You can buy cheap hydrogen peroxide here.
The great thing about the paste method is that you don’t have to use lots of peroxide and it can be spread in all those weird nooks and crannies skulls have. The only annoying thing is that you will have to do at least two rounds – one for the top of the skull and another for the bottom.
With this method, the hydrogen peroxide is only getting on the exterior of the bones. It WON’T get into all those little nooks/crannies that skulls have. For example, the inside of the brain cavity and foramina will not be cleaned. So, if the skull is fresh and might have some tissue lurking, I’d play it safe and soak it completely in hydrogen peroxide + water.
If you need to save on peroxide, one option is to soak the entire skull in a very diluted solution of hydrogen peroxide + water. Then go at it during a second round with the paste. The first round will get inside the skull. The second round with the paste will whiten the heck out of the skull. Just make sure you drip the paste down any nooks, crannies, and foramina!
Here you can see the before/after pictures.
The skull is hanging in my daughter’s room, right above her Hello Kitty covered bed with a mountain of stuffed animals. The perfect décor for a little girl. 🙂
Yet another method: Paint on cream hair developer
As I mentioned before, cream hair developer has emulsifiers added to thicken it. What’s cool about this is that you can paint it directly onto bones. There’s no need to mix it with baking soda to thicken it! After applying, cover the bones with plastic wrap. Otherwise the cream developer will dry out too quickly.
Like with the baking soda paste, this method also won’t clean the interior of the skull. Make sure your skull is completely clean of tissue before you try to whiten it by painting on cream developer.
Here is in infographic form. Feel free to Pin It! 🙂