Maceration 101- How to Clean Bones with Water

What is Maceration?

In terms of cleaning bones, maceration is the process of using naturally occurring anaerobic (don’t need air) bacteria in water to decompose flesh, ligaments, and tendons to leave us with nearly clean bones.

What Materials are needed to clean an animal skeleton with Maceration?

When to Use Maceration

Maceration causes ALL bones to come apart and makes teeth fall out, so it is not recommended for small animals if you plan on articulating them. The smallest I have macerated and then articulated was a squirrel, and seeing those tiny carpals and tarsals (wrist and ankle bones) was extremely hard. I’ll make another post on how to clean small animals soon.

Maceration is known as one of the worst smells on this planet. The stench will travel quite a ways, and will stick on your skin for several days, so it is not recommended to use maceration if you live close to people that will be bothered by the smell.

How to Prepare an Animal for Macerating

If you’re starting with a full animal, you have a good bit of work to do before you should start macerating.

1. You’ll want to skin the animal. Macerating a full animal with skin on will take months, and it still won’t be clean, so don’t be lazy. Get out a knife and skin it. Pick up a gross roadkill animal and don’t want to skin it? Don’t be a baby. Skin it.

2. Gut it. Guts are gross, but they’ll make a big mess when dumping, so it’s best to remove them all. Eyes, lungs, heart, and all other organs need to be removed. They can be taken out all at once (excluding eyes) if you have some skill/experience.

3. The second most important part if you want to macerate things quicklyfleshing! This is often the step that people skip or slack on, and is why it takes them a few months to macerate things where it only takes me a week- two weeks tops. The more meat that’s left on the bones, the longer it’ll take to be broken down by the bacteria. Fleshing well also reduces the chance of adipocere (“grave wax”) from accumulating on the bones.

  • Get a scalpel and cut off the head, cut out the tongue, and remove as much meat from the head as possible. Then remove the brain. This can be done with a brain blaster (I’ll make a post about it eventually), or by using a tool (scalpel, forceps, skewer, or anything else) to slosh the brains around, and then gently wash them out with water via faucet or hose. The pressure from the water should force the bits of brains out and down the drain.
  • Cut off the front legs by going behind the shoulder blade, but be careful not to damage the clavicle (collar bone) if the animal has them. 
  • Then cut along the sides of the top of the spine and remove the back muscles. 
  • Cut between the ribs and cut off the costal cartilage (the cartilage that attaches the ribs to the sternum)- it’s white and can easily be seen from inside the rib cage. A pair of wire snips or scissors are sometimes needed to cut through it. Maceration will break it down, but it’ll turn the consistency of coral and won’t be usable, so it’s less to sort through later if you remove it now. Remember to not throw away the sternum! Cut the cartilage off of it and put the sternum in your maceration container. 
  • Remove the back legs by finding the ball joint of the hip and cutting behind/around it. There’s one strong ligament attaching to it on the inside, and once you cut it the femur should pop out of the socket. 
  • Cut all large muscles off of the front and back legs. Remove the meat from the back of the shoulder blades, the two large chucks on each side of the ridge on the scapulae, cut to the side of the humerus (upper arm bone) and peel back the muscle. You’ll have to cut a bunch of tendons at the shoulder joint to get the muscles to free. Cut along the upper and lower side of the ulna or radius (forearm bones) and remove that meat. Then remove the meat and ligaments on the bottom and tops of the paws/hands. Repeat these same steps for the back legs. Be careful not to remove the patellas (knee caps) when fleshing the legs.
This is how the animal should look after you're done fleshing. Very little meat left on the bones. Removing the ribs or cutting the legs apart like I did is not necessary.

Prepping The Death Bucket

After your animal is prepped for macerating, simply put it in a container that can hold water and be sealed. I usually put the head in a separate container to reduce the risk of losing teeth in the maceration goo during dumping. A 5gal bucket, pickle jar, or any other container that be sealed will work. Then fill it with water- tap water will work fine. You can spit in the bucket if you think it will help the bacteria, but the enzyme in your spit (salivary amylase) breaks down starches, not proteins, which won’t help us much. You’d need some stomach enzymes (pepsin) in there if you wanted to break down the proteins. You don’t need to add anything besides water. No aerator, no drain cleaner/septic chemicals, no washing powder, no peroxide, JUST WATER. Seal the container and keep it warm. Heat is the most important part if you want to macerate quickly. This can be accomplished in a few ways:

  • The best way, and the way I currently use, is with a heater. You can use an aquarium heater, but that requires getting the heater yucky, and some heaters require you to override their temperature controls, which seems unsafe to me, so I used a thing called a Pail Heater. It wraps around the outside of a 5gal bucket, and has a built in thermostat. The thermostat is in Celsius, so you’ll have to do conversions. The heater is a bit pricey ($50-60), but they last a very long time (I never had one burn out) and work very well. Ideally you want the temperature anywhere between 80-115F (26.6-46C) If you forget that the thermostat is in Celcius and accidentally set it to 80-115C you will melt your bucket and potentially start a fire. At 115F (46C) the bacteria will not be killed, and the bones will not be damaged…. We’ll cover temperatures more when we get to Degreasing. Just know to NOT BOIL OR SIMMER the animal to clean the bones.
  • If you don’t have a heater, you can keep the container outside in the sun during the warm months. Painting the container black will help keep it warm. The cons to this method is the container will cool at night, and the bacteria are most efficient at constant temperatures. It’ll still work, just slower.
  • No heat! Known as cold water maceration, as long as it remains at least 60F+ (15.5C+), it’ll still work, just very slowly. This means you can technically macerate things just by bringing the container inside, but I do not recommend it. This method can take months to clean, and the lack of heat will increase the chances of adipocere (grave wax) on the bones.

How/Where/When to Dump Maceration Buckets

If your container is heated, I advise dumping it once every week or two. I personally dump every weekend. Maceration liquid STINKS. You’ll need a place to dump the goo that won’t bother people or wildlife. Do not let pets or wildlife get in/eat your maceration goo. It can make them very sick. It is THRIVING with bacteria, so make sure to wear gloves and make sure it doesn’t get in any cuts/wounds. If some does, immediately wash the wound and use alcohol to disinfect it. If you don’t, it can lead to cellulitis (HORRIBLE infection) which can lead to you literally having to have your limb amputated. It’s not something to joke about. It messed up my thumb pretty bad once, and I have friends that were hospitalized from it. There are many setups you can use to dump your death soup:

  • My current dumping setup in my new studio has plumbing, but I know most people won’t have that luxury. What I used to use was a 5gal bucket, an about 10′ long 3″ pipe in an L shape, and a hole. I cut a 3″ hole in the bottom of the bucket and siliconed it to the shorter end of the L shaped pipe. I then had another 5gal bucket that I drilled small holes in the bottom of that I’d place in the first bucket. The top bucket was used as a secondary strainer to not lose bones/teeth. At the end of the pipe I dug a decent sized hole where the maceration goo could land. It would be absorbed into the soil by the next time I dumped. I’d dump my goo in the top bucket, the liquid would go through the holes into the second bucket, then through the hole, down the long pipe (far away from me) and land in the hole. Kept me clean and my workplace less smelly.
  • A simpler setup is to dig a temporary hole. Dump your goo in there (make sure to use a screen or strainer so you don’t lose bones) and then fill the hole back in when you’re done. This is good for the smell, and can be used almost anywhere.
  • Another option is to use it as fertilizer! Maceration is just decomposed animal matter, water, and bacteria, which is great for plants! Make sure not to dump it directly on any produce that you’ll be eating (potatoes, carrots, or anything else grown under the ground) and make sure not to splash it on any foliage or produce that you plan on eating.
  • You can also dump directly into a toilet. I would never do this, as it would stink up your entire house for DAYS, but it can be done if needed. Once again, use a strainer to make sure you don’t lose any bone/teeth. It’s just bacteria and decomposed meat, so it won’t hurt your plumbing or septic.
This is what you'll see if you don't flesh well. I believe this was a roadkill cat that I skinned and gutted, but did not flesh. After a week of macerating (outside- unheated) it was a green, smelly, mostly intact mess.

If you notice that there’s still meat/ligaments left on the animal when you’re dumping, don’t dump all of the liquid out. Leave a small amount left (25% will definitely do) and refill the container. This will help not kill off the bacteria and will help finish up macerating. Let it sit for another week or two, and then dump again. Repeat until the bones are flesh free.

This was a coatimundi that I dumped after one week and noticed wasn't ready, so I left a little goo in the bottom to boost the bacteria. This bucket was outside but was not heated.
This is one of the more appealing looking maceration buckets I've opened. It had the African porcupine that's in the next picture in it. They often have grease, blood, and small chunks of meat floating on the surface. This bucket was heated.

If the bones look mostly flesh free and are no longer connected to each other, use a water hose to rinse them off and dump again. This rinsing will get a lot of the remaining gunk off the bones and let you see if they’re done macerating. If they look like the next picture, they’re done macerating and ready to begin degreasing. If you see a white substance on some bones, you need to read How to Remove Adipocere/Grave Wax

This is the African Porcupine from the last picture after one week of macerating. Completely flesh free. This bucket was heated.

What Do I Do Now?

If your bones are now flesh free, you’re ready to start degreasing them! Go on over to the next article, Degreasing 101!

If you found this article helpful, feel free to leave a comment down below or share it with your friends! I don’t get anything directly from making these guides, but it saves me time answering questions and helps you all so I’ll continue to do it! I don’t ask for/accept donations, but feel free to grab something small from my Shop or follow me on my social media (InstagramFacebook, or Tumblr) if you’d like to support my work!

If you noticed any typos while reading this, any links don’t work, or have any suggestions or questions that weren’t covered in this article or the other articles on my Blog, please leave a comment below or Contact Me

6 Responses to “Maceration 101- How to Clean Bones with Water

  • Brenna Bigge
    7 months ago

    Do the sealed buckets themselves smell? My plan was too keep them in the barn and then take them down to the back of our property to dump. I don’t think my mom would be super happy if they smelled up the barn.

    • If it’s completely sealed, there should be very very minimal smell. Just DO NOT open the bucket in the barn, because then it will absolutely smell.

      • At the beginning of this post you mentioned not using this method for small animals. What is the preferred method you used for anything squirrel, rat, or smaller? I plan to clean mouse in pretty decent numbers.

  • At the beginning of this post you mentioned not using this method for small animals. What is the preferred method you used for anything squirrel, rat, or smaller?

    • If you intend on articulating them, I would recommend using beetles. That’s the best way to keep the tiny bones mostly together during the cleaning process. -Dalton

      • I plan on using the skulls mostly. I may try maceration and see how it goes. Or get myself a nice cage setup and try just natural decomp.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.