Flock You, Borax: Tanning Mammal Hides for Taxidermy

posted 2024 Apr by Paloma Strong

When working on mammals for taxidermy, you have to go through a biochemical process to stabilize and preserve the hide. Leather making is an ancient art and proves to be a great way to preserve animal hides for long periods of time. Although the specific techniques have changed over the centuries and throughout the world, there are still some simple steps that you have to take to properly preserve a hide. The word "tanning" originates from the compounds known as tannins, which can penetrate the deepest layers of the skins and bind with proteins to stabilize and enhance their preservation. Most of the tannable compounds in the skin will be collagen, however there are other parts of the skin that have tannable proteins as well. There are many different types of tanning so I wanted to create an easy guide for people who are just getting started on their taxidermy journey and are looking into how to best preserve raw hides. A common misconception is that a skin can be stabilized using just salt or Borax. Borax is one of the worst things you can put on a skin to "preserve" it - it does nothing to preserve the skin and can prevent a proper tanning in the future. While this can deter some pest activity, drying out the hide is not a sustainable preservation method and needs to be followed up with other processes to ensure the specimen is not only viable for taxidermy, but will stay together for many decades to come. 

Raccoon museum taxidermy

 

Pre-tanning Notes

When you receive a specimen, you will either get one that is "whole frozen" or "green". Whole frozen describes a specimen that has been put directly in the freezer. "Green" describes a specimen that has been skinned out, but still has some tissue still on the skin, perhaps needs some more facial details done, and could even have some bones left in the toes. In order for a specimen to be viable, it should be placed in the freezer with in a few hours. If you are purchasing a specimen from a supplier, this will absolutely be the timeline that they are getting a specimen in the freezer. In California, it is currently illegal to pick up roadkill for personal use. Please follow your state and federal laws when you are sourcing specimens. If you are unsure about the laws, please contact your local game warden or Fish and Wildlife for guidance. The laws are in place for your safety and the conservation of our native species, so please keep legal. 

Salting

Once you have skinned out a specimen (including every single toe bone and skinned out the facial details), you can begin the tanning process. Salting is the first step to preserving a hide. The goal is to cover the entire skin with salt so that no skin is touching itself without a layer of salt in between. After 24 hours, shake off the excess salt and re-salt. Keep repeating until the animal is crispy. Any large quantity of salt you can get your hands on will do. Again, Borax is not a preservative and will break down mammal hides over time. At Prey, we only use Borax when fluffing very large birds (think Pelican size) to help speed up drying, but it is by no means a preservative of any kind. 

Acid pickle

For every step of this submersion tanning method, you need to make sure you are adding plenty of salt to the mix. Salt will ensure that there is no acid swell, which can cause a skin to deteriorate and fall apart. The length of time a skin will be in pickle will be dependent on how large the specimen is, how much tissue is still present, and how greasy the skin is. Take your specimen out of the pickle at least once a week to flesh and check how the pickling process is going.

A successful pickling solution will have a maintained pH of 2 or below. There are many commercially available pickling agents; we recommend using Formic acid or Knoblochs Safety Pickle. For every gallon of water, add 1lb of salt and 20mL of the preferred acid. Please follow the formulas on this page for Safety Pickle. Be sure to check your pH regularly. 

Skunk taxidermy tanning for museum taxidermy

 

Pre-wash

For greasy skins, you will need to do a pre-wash before the tanning step. We recommend a soak and scrub using a salty bath and a capful of Kemal-4, which is a detergent-type degreaser and easily cuts through any leftover greasy. If you have a particularly extra greasy skin, look into Super-Solv Degreaser. You can also do Kemal-4 baths during the pickling process to remove grease over time and throughout the pickling process. Prior to the tanning step, you must neutralize the skin to at least a 6 pH using baking soda or another basic compound, otherwise the leftover acid will break down the hide.

Tanning

Tannins, which are available commercially and derived from natural plant compounds, interact with tannable proteins (mainly collagen) in the hide. Forming chemical bonds in the main structural proteins of animal skins will prevent the hide from breaking down over time. For traditional taxidermy, we use Lutan-F. There are other options to use commercially, however - make sure you read the label and use as directed. There are alternative methods to tanning, such as brain tanning, but we are describing the typical commercial process used in our museum work. I would highly recommend doing some research and learning about brain tanning, as it is a very interesting process that uses the specimen's own brain to process and preserve the hide.

Oiling the hide

Oiling leather will serve to soften a tanned hide, and provide extra protection. There are several types of tanning oils that are used commercially in taxidermy. For traditional taxidermy mounts, we use Tanning Oil #1. Make sure to cut any oil in half with water and heat up in the microwave for about 30 seconds. Apply to the inside of the skin with a chip brush. This is the final step of the tanning process, whether you are using the hide for traditional taxidermy, soft tans, or any other project you are working on. After oiling the hide, you have ~officially~ and ~successfully~ tanned your mammal specimen.

Fox mammal taxidermy

 

Storing the hide

You should roll up the skin like a burrito and "let it sweat" overnight. The next day, put in a Ziploc bag and store in the freezer until you are ready to put together your mount.

If you are interesting in having a soft mount, you will need to break the hide in order for the skin to be malleable and soft. There are two common options: tumbling or drying. If you have a large tumbler, you can place the hide in the drum with sawdust and the motion will help break it. You can do a similar process using a dryer with no heat. Pull the skin out occasionally to work the skin while it is drying to really solidify the breaking of the hide. There are commercially available products that will help assist with the breaking process, like the tanning oil Protal or the Breaker tool from Van Dykes.  

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Tanned Skins for Mammal Taxidermy Key Points

Tanning hides for taxidermy is a great process for a taxidermist of any skill level to learn. If you do not have the space or desire to tan your own specimens, there are plenty of reputable tanneries that will process your skins for you. You can also purchase tanned skins if you want to begin with a preserved hide and not go through any of the tanning process. Tanning your own skins is beneficial since you are able to work with the specimen from start to finish and learn about every issue and benefit of the individual. 

While we don't have any in person courses that have any hands-on experience with the mammal prep and tanning process, each student who completes a mammal course will receive documents and resources to get through their project. Since this is a process that can take several weeks to several months, it would be very difficult to use our usual 2-day curriculum applicable. This would make for a very expensive class when the process itself is quite simple and cheap to do at home. Rather than charge for a tanning class, we would rather get a good informational guide out there to help you get started on your taxidermy journey. 

Thanks for reading! I hope this is a helpful guide to help you on your taxidermy journey. The real reason I wrote this blog is because we are so over seeing that Borax is used to preserve mammal skins - because it really doesn't work. Flock you, Borax.

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