My strange and wonderful 6-year old has an obsession with bones. 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. 🙂
I read a lot about how to clean bones on the web and have now tried it many times. Here’s a quick overview:
- Never use bleach to clean bones. It will destroy their structural integrity.
- If the bones are fresh, you have to remove soft tissues and “degrease” them first.
- Only boil bones to clean them if you have no other means. They look yellow and terrible when boiled (because boiling traps the fat inside the bones).
- Hydrogen peroxide is the best amateur method for whitening bones.
- Hair developer is the same thing as hydrogen peroxide.
- You can mix hydrogen peroxide with baking soda to form a paste. This can be applied to large bones which are too large to soak.
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?
The hydrogen peroxide that you buy in drug stores comes in really small bottles, and is usually at a concentration of 2%.
Yes, you could use this hydrogen peroxide on bones, but you’d need a LOT of it and have to soak the bones for a long time. Instead, ask your pharmacy for bulk hydrogen peroxide at 20% (or higher) concentration.
I couldn’t find any pharmacy which carries 20% hydrogen peroxide, so I had to find a hookup who works in a pharmacy to special order 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. It is basically hydrogen peroxide (with some perfumes and alcohol mixed in). I’ve since lost my pharmacy connection, so used this to clean a few small skulls.
The only difference is that it is “stabilized” so it won’t foam up like normal hydrogen peroxide — which actual makes it easier to apply like a cream over your bones instead of soaking them in it. You can buy 12% hydrogen hair developer on Amazon here.
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 easiest 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. I live in the city, I don’t think my neighbors would like to see (and smell) rotting bone tissue in our communal yard, so I personally have never done this.
Method 2: Burying
Alternatively, you can bury the bones. Bacteria will eat away at the bones (and maybe some worms 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 best, fast 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.
*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!
Method 4: Boiling (NOT RECOMMENDED!)
Boiling bones will loosen soft tissue and cause it to fall off very quickly. However, it 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 get into the bones when boiling.
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.
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. 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 are lazy and skip degreasing, you’ll probably have to do 2 rounds with hydrogen peroxide.
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.
I couldn’t find any information about the exact ratio of hydrogen peroxide to water for cleaning bones. Basically, 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.
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: Keep the bones out of sunlight while they soak. Hydrogen peroxide is deactivated by light!
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.
I didn’t have a lid for my bucket the first time I cleaned some bones. So, I just put a plastic bag over the top to seal the bucket.
*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 cleaned it with soapy water (skipped the soaking step though because we were in a hurry to finish before moving to a new home).
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 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
Update: I’ve since switched to using hair developer instead of hydrogen peroxide. Hair developer is just hydrogen peroxide which has been stabilized (so it won’t foam). It mixes beautifully with baking soda to make a paste you can spread onto bones for cleaning them. You can buy cheap hair developer 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.
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. 🙂
*Using the Paste Method on Fresh Skulls:
I’ve only used this on skulls I found in the woods, meaning that the skulls were already very clean (no brain tissue lurking inside!). However, I did have one reader email me with pictures of a fresh deer skull she cleaned beautifully using this method. 🙂
If you are going to use paste on a fresh skull though, the skull better be clean of all soft tissue – including brains!
When you soak skulls in hydrogen peroxide, the solution gets into the brain cavity and the foramina (those little holes for nerves you can see in skulls).
By contrast, the paste only gets on the outside of the bones. It won’t loosen any residual tissue lurking inside the skull (and there might be a lot of it, as I learned when I started soaking my boiled pig skull).
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 is in infographic form. Feel free to Pin It! 🙂