Mom Goes Camping

How to Clean Animal Bones Using Hydrogen Peroxide and Baking Soda

how to clean bones using hydrogen peroxide and baking soda

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.

Jump to:

 

Gourmet As Heck ebook

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.

hydrogen peroxide 40%

This giant bottle of hair developer (hydrogen peroxide) is 12% and is really affordable for a gallon. Buy it 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.

Supplies:

  • 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.

*Steaming:

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!

boiled pig skull

Isabel got this pig skull as a gift. It is yellow and shiny from being boiled.

 

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.

 

Hidden Tissue

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.
cleaning bones of hidden tissue

Notice the gross tissue that started to come out of a hole once the skull was soaked!

 

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 one in cleaning animal bones

This gives a new definition to brushing your teeth!

 

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.

Check out how greasy this possom skull is! It needs hardcore 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.

container for cleaning animal bones

cleaning animal bones - adding hydrogen

Adding peroxide to the bones

Hydrogen for cleaning bones - starting to foam

The peroxide is starting to foam!

whitening a cat skull

And here’s a cat skull soaking in hair developer + water. This one was done with cream hair developer, which doesn’t bubble as much as clear hair developer.

 

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).

before after cat skull cleaned

 

*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.

steaming bone in hydrogen

Check out the steam coming off this dirty 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. 🙂

cleaning a hip bone

So many bubbles!

bone before and after

Bone before and after cleaning.  Not completely white, but still beautiful!

 

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!

cleaning a cow skull

Notice the whiter line from my first attempt at cleaning the skull.  Note that I shouldn’t have whitened the horns.  They look much better natural.

 

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.

This is the paste I made from baking soda and hydrogen peroxide

This is the paste I made from baking soda and hydrogen peroxide. It was about as thick as toothpaste.

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.

Applying the paste to the skull. It started foaming quickly, but the paste didn't fall off.

Applying the paste to the skull. It started foaming quickly, but the paste didn’t fall off.

 

Note: 

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.

before after skull cleaning

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.

whitening bones with hair developer

Pig skull with cream hair developer painted on it.

 

Here is in infographic form.  Feel free to Pin It! 🙂

How to clean bones infographic

 

About the author /


Diane Vukovic is an avid traveler, outdoor enthusiast, beetle lover, sometimes sculptress, couchsurfer, and loves finding ways to explain complex topics to her 6-year old daughter. Follow MomGoesCamping on Facebook and Twitter @MomGoesCamping to stay in touch!

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17 Comments

  1. Bethany

    With the paste method, how long did you leave it on? Did you scrub it with the toothbrush, or just apply and let it sit? After soaking or past methods, do you just rinse with water? Thanks!!

    • Diane

      I used a toothbrush to apply the paste. No scrubbing needed. I had planned on leaving the paste on at least overnight… but then it started to rain. So, it ended up being just about 5 hours or so. The rain rinsed it off! If it hadn’t rained though, I definitely would have rinsed it with water. Note that the baking soda and hydrogen peroxide solution will bubble up when you make the paste, but it still works well. I have since switched to using hair developer instead of normal hydrogen peroxide. The hair developer doesn’t bubble so works better for making a paste. (I’m going to write a post on that method soon!) *If your bone is small, it’s probably better to just soak it in hydrogen + water. That ensures the solution gets into all the nooks and crannies. Otherwise, you’ll have to apply the paste more than once, since you can really only do either the top or bottom at a time with the paste.

  2. Rachel

    What ratio of baking soda to hydrogen peroxide did you use?

    • Diane

      It is probably around half/half, but I don’t measure. I just add enough of each to make a paste which was about as thick as toothpaste. If you are using hydrogen peroxide (and not hair developer), it will bubble when you mix them. Just spread it as it bubbles. Good luck!

  3. Robsaint

    Here’s another great way to save on peroxide for large skulls;
    Put the skull in a bin bag.
    Place the bin bag inside a bin or other large container.
    Fill bin/container with water. This pushes air out of the bag making a snug fit around the skull.
    Fill remaining space inside bag with 50/50 peroxide/ water. Thus using far less peroxide and getting great results.

    Discovered this method from fellow skull collectors on Facebook groups.

    • Diane

      That’s a great trick! With the cow skull shown in the article, I tried putting it just in a bag and the bag broke (which is why there was a white line around it from where the h2o2 accumulated at the bottom of the bag). Putting it in a bin and filling it with water would have prevented the bag from breaking. Thanks! 🙂

  4. Alona V.

    Hey guys! There is no way for me to get a good amount of hydrogen peroxide in my country. In case the bones don’t have any tissue on them would soaking them for a few days in hot (but not boiling) water with laundry detergent, replacing the solution every 24 hours and occasionally brushing it with baking soda\toothpaste and tooth brush be good enough?
    I am not very interested in whitening the bones, maybe just a little bit.
    Thanks.

    • Diane

      Most laundry detergent has bleach in it. It will clean and whiten the bones… but bleach will make the bones turn flaky after a while. Even if you can’t find hydrogen peroxide in big bottles where you live, you probably can find hair developer (that’s what I use now). Just go to a beauty supply store and get it. Use it + some water for soaking the bones. They will be clean and whiter. 🙂 For a large skull, you can get by with just 1 liter of hair developer (costs about 10-15 euros in beauty stores). To save on it but still get the skull clean everywhere (including inside all those foramina holes), I first soak the skull in water with just a bit of the hair developer. After a day or two, I dump that solution. Then I’ll apply a paste made from the rest of the hair developer and baking soda.

  5. Kaylin Brodzki

    Are these methods safe to use on bird bones? I’m a little worried about weakening or breaking the bones of this beautiful specimen I found while cleaning my patio for spring. The remains are already mostly clean, however there is a bit of tissue I still need to clean off…

    • Diane

      I am working on my first bird specimen right now (a complete baby bird that I found dead on the sidewalk). So, I can’t say for certain. Soaking in water to remove the tissue shouldn’t be a problem though. My bird is soaking in hydrogen peroxide right now and seems to be okay. The H2o2 seems to have removed the remaining bits of feather/gunk that was stuck to the bird and I couldn’t get off/was too lazy to get off with tweezers. What I’m worried about is articulating the bones back together afterwards. If you have any tips for how to do that, please let me know! Oh, and (as with horns) you might not want to use the hydrogen peroxide on the beak if you want it to remain a natural color. In this case, maybe try painting the H2o2 onto the bones (after soaking to remove all the tissue) instead of soaking it in the H2o2. That will give you more control over where the whitening occurs.

  6. Name *

    Hello I Have A dog skull i’ve dryied the skull and i cleaned it but it still have some bad smell can you lead me please what to do Thank’s

    • Diane

      Sometimes bones get a weird smell when they are still wet, but it goes away when they are dry. However, if the bones are dry and still stink, then it is probably because there is still lots of grease in the bones. You’ll need to:
      -try degreasing (soaking in soapy water) again. You might see some nasty tissue you missed float up too! Yellow spots on the skull are a sign that there is grease trapped inside.
      -Consider removing the teeth (carefully – they crack easily). There could be some nerve endings or other tissue stuck under them. Reinsert the teeth while the skull is still wet or they might not fit back in.
      -Use a wire to poke into any holes in the skull. There could be tissue lurking in there – especially if the skull was boiled to clean tissue off.

      After soaking/degreasing again, do another round of hydrogen peroxide. Put it outside to thoroughly dry. You can also soak it in rubbing alcohol to force water out of the skull, but this is probably not necessary.

  7. Name *

    Hi there! Just wondering, what if you have just a turtle shell? Could you just clean with soapy water? Or is there a way to disinfect it without changing the color? Thanks!

    • Diane

      I’m not 100% sure. A couple of months ago, I found an old turtle shell. The actual shell part was white bone. Next to it was a curled up piece of the shell cover. So, it made me realize that the colorful part of turtle shells (the part with the pattern) are like a fingernail cover that goes over the bone (the same goes for animal hooves)!

      I would NOT clean it. The first reason is that cleaning it would likely cause any connective tissue holding the pieces of shell together to come apart. Speaking from personal experience, it is insanely difficult to piece together a turtle shell. I managed to glue my pieces together, but there are big gaps since I had to get the pieces from multiple angles (it’s not like a puzzle where you snap one in at a time).

      The second reason is that the colorful cap could get ruined or come off.

      If it doesn’t stink, just let it be. If it does stink, maybe try painting some hydrogen peroxide on the underside (NOT THE TOP OF THE SHELL). I guess you could use a toothbrush to scrub it with soapy water, but I wouldn’t soak it. Soaking it causes a bit of expansion then shrinking, which could cause the bone parts to come apart and also separate from the colorful “nail” part.

      Hope that helps. Again, I’m not 100% sure about this so don’t blame me if something gets screwed up 😉

  8. Dawen

    Hi, I’m mostly concerned with sanitization. I found bones on the beach which are completely stripped of flesh. Right now the color is amazing and I don’t really want to whiten them. Currently I’ve got them in water and Dawn dish soap for degreasing (I’ll see if that affects the color at all, I guess). Would that be enough to sanitize them? Or do I still need some hydrogen peroxide, and if so, what’s the minimum I could get away with?

    • Diane

      If they’ve been on the beach for a long time, the exposure to sun and salt water should be more than adequate to sanitize them. If you like the color, then don’t do anything at all 😀

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