Cleaning an antlered deer skull using maceration.
Maceration is the process in which bacteria produces enzymes which break down organic matter. Putting a skull in a bucket of water and letting the bacteria grow and macerate a skull is actually the same thing that is going on in your stomach right now! So just think of the bucket as a stomach! Just to clarify as you may have seen the following terms mentioned around, warm water maceration vs cold water maceration is just that, one is warm and one is cold.
The process of cleaning a deer skull using maceration is very simple, you just need water. But there are some key points in the following instructions to be aware of. I have gotten 100s of questions regarding this process so the information in this article is written to answer the most common questions people have. The following will take you through cleaning the skull using maceration, degreasing the skull, and whitening the deer skull. Just fyi this article includes affiliate links.
Materials needed are a bucket, aquarium heater or bucket heater (optional), large trash bags, zip ties or chip clips, dish soap, and hydrogen peroxide.
You can see the how to video that goes with this article here.
► Skin the deer head out. I start my first cut at the back of the mouth straight back to the neck, and then work my way around the skull. Leaving a bit of the hide around the antler bases is ok as it will come off in the macerating process. You do not need to do anything else such as cut off meat, cut out the tongue, take out the brains, etc. You can do those things if desired (it will help with corpse wax discussed later) but I do not. You can also start with a skull that is in any other condition (previously boiled, a dead head, a mummified head, etc.).
► Put the skull in a bucket and fill up with clean water to about 1 inch above the back of the skull. City water or well water works just the same. Make sure the entire skull is submerged. Add in your aquarium heater or bucket heater and set temperature to 80-100 degrees Fahrenheit. I use a 100 Watt Aqueon Aquarium Heater and a small foam insulated bucket heater. If you are not using a heat source set the bucket in a warm place. You can secure the skull to the side of the bucket with zip ties as the skull will want to float as the tissue starts to break down. You can also prop up the antlers with another bucket to keep the skull from tipping forward and floating. Take a large trash bag and put the entire bucket into the bag. Cinch up the bag with the heater cord coming out of it and either zip tie it shut or use a chip clip to seal the bag shut. Putting the entire bucket and skull inside a bag minimizes the smell from the maceration. Does it smell? Yes, yes it does. The worst of the smell will be the about the 2nd and 3rd time you change the water and then it dissipates after that. I personally do not find the smell overwhelming and regularly clean skulls in residential areas with no complaints at all. Do remember to take any precautions from animals such as dogs from getting to and messing with the bucket. There is no need to add any type of booster such as Rid-x, the process is quicker than you realize and introducing something into a process that is already working great is not needed.
► Change the water every 2-3 days. If you are not using an aquarium heater or bucket heater this time frame may vary. The bacteria grows best at higher temperatures so colder weather could extend the time between changing the water. Each time you change the water brush off the antler bases with clean water making sure there is no grease/grim attaching to them. I do not wrap the bases of the antlers because I am changing the water often and keeping the bases free of grease (which could stain the bases). In order to minimize the chances of losing teeth remove the lower mandible incisors (if you are keeping the lower jaw) as they become loose. Make sure all the teeth are accounted for and that you do not lose any when you dump out the maceration water. You can opt to dig a small hole to pour the water into as this seems to help minimize the smell when changing the water. There will be enough bacteria on the skull itself to propagate the fresh water when you change it. Some people say to add beer, spit, forest dirt, fresh meat, etc. in between changing but in my experience it is not needed at all. You can opt to leave a bit of the previous water in the bucket to help propagate the fresh water. I believe I changed the water on this skull 7-8 times so about 15-20 days total to fully clean. Oh and the brains will just turn to liquid so watch your toes when pulling the skull out of the water!
There are two main types of bacteria, Aerobic bacteria and Anaerobic bacteria. Aerobic bacteria grows rapidly and needs oxygen present to thrive. Anaerobic bacteria on the other hand grows much slower in an environment with a lack of oxygen. Changing the water every 2-3 days allows the aerobic bacteria to flourish as you are using fresh water with oxygen. If you did not change the water the aerobic bacteria would die off after a few days and then anaerobic bacteria would start to grow (using noticeable due to causing a reddish/brown color to form on the bones).
► Continue to change the water every 2-3 days until the skull is fully clean. If the water continues to get cloudy or the water continues to be really smelly keep macerating till these conditions are gone. The skull may still have an odor when it’s done macerating (before degreasing/whitening) but as a general rule if the water is really smelly than means there is still organic matter in the skull that needs to be cleaned. Due to the maceration process doing such a great job some bones may be loose such as between the antlers along the sutures and some may come off such as the premaxilla bones and nasal bones at the end of the nose. This is typical and should be expected. You can glue these back on at the very end once the skull is degreased and whitened. You can see more on the topic of the bones getting loose in this video.
► Let the skull dry out at room temperature. There may be a white/pinkish substance that is still on the skull which is called corpse wax (Adipocere, grave wax, or mortuary wax). This waxy substance is a leftover fatty organic substance that has saponified (the process of turning fats into soap). You can scrape, brush, or use a soda blaster to remove this chalky substance before moving on to the next steps. You can read also read “Adipocere 101 – How to Prevent and Remove Grave Wax From Bones” or see how I remove it with a soda blaster in this video. As noted in that article changing the water often and removing as much tissue at the beginning of the process can cut down on the formation of the wax.
► Using the same setup as the maceration put the skull in a bucket of clean water and heat source and add approximately 1/3rd cup dish soap to the water. Change the water every 3-5 days till the skull is fully degreased. You can position a trash bag over the top of the bucket in between the antlers in order to seal the bucket. The process of maceration does actually degrease the skull to some extent which shortens this step. Grease in the bone generally shows up as a yellowish color. When the skull is dry it can also appear like there are “wet” areas underneath the bone which is a sign there is still grease in the bone. Each skull is different so the time it takes to fully degrease will very. Typically a fresh deer skull that has been macerated as described above takes 1-2 weeks to degrease in a heated bucket. Take that time period with a grain of salt though, as it could take much longer.
You can also use ammonia or acetone to degrease the skull. Please see the article “Degreasing 101- Three Ways to Turn Yellow Bones White” for more information on this method.
► Let the skull dry out again and assess if there is any remaining corpse wax or grease that needs to be removed. Using the same setup fill up the bucket about half way with 3% hydrogen peroxide and half with clean water. Wrap the bases of the antlers with clear food wrap and electrical tape really tightly in order to prevent the bases from becoming whitened. Add the skull into the bucket with the aquarium heater or other heat source and add the trash bag over top. Leave the skull for 1-3 days or more till whitened. If you follow the above steps you do not need anything more than 3% peroxide. If the skull is properly degreased it will already be white so the 3% works just fine. It takes about 8 bottles of peroxide which is less than $8 and you can use the solution for several skulls making the cost of the peroxide for a skull less than $3.
► Rinse the skull off and let dry at room temperature. Do not expose the skull to rapid changes in temperature as this can cause the bones to separate.
► Add back any loose teeth with Elmore’s glue and glue on lower mandible if desired. And that’s it!
There has been a shift toward cleaning skulls using this method due to the how gentle the process is on the skull thus resulting in a complete skull that is museum quality. Not to mention not having to maintain a beetle colony or damage skulls via the process of boiling. The time frame will vary depending on the skull but for the skull used in this example from start to finish took about 1 month. Very greasy skull like bear and hogs can take much much longer just so you are aware. I personally clean all my skulls using this method and like I said earlier I live in town! If you have any questions you can message me on Facebook or Instagram! ~ Hunter Richardson