An Intro. to Tanning and General Preservation

Hello everyone! I've found myself with some tanning downtime due to the fact that we are out of Lutan and are waiting for our order.  As such, I have ample time to gather my thoughts and put them into journal form on various topics! I'm thinking of doing several 'chapters' under different topics such as this one (Tanning and General Preservation,) Freezing and Thawing, Pickling and Other Chemicals, and more~ I've done research, asked questions, read many books, and also been through over five years of trial and error in tanning so I believe I would have a lot to offer if I put this idea into motion. If you would like to see this come about, let me know and I'll actively start getting everything together instead of just letting it kick around. In this journal I will talk about the difference between true tanning and general preservation of skins.

True Tans

Tanning, by definition, is "The processes of treating skins and hides of animals to produce leather." An expanded definition goes on to state that the 'leather' produced from the tanning process will be moisture tolerant, durable, pliable, and resistant to mold and insects. This is what I refer to as a 'true tan,' which will not deteriorate or lose hair if moistened after the process.

The reason I make this distinction is because some processes claim that they are tanning when in reality they are just working a surface preservative into the hide until it's dry. If moistened, the preservative will wash away and once dried the skin will essentially turn into stiff rawhide, if it doesn't decompose. A true tan will not only penetrate into the fibers of the skin but will permanently alter their structure on a molecular scale.

For example, a 'brain tan' alone is not a true tan. You can rub brains into a hide all day long but until you smoke the hide for several hours over a fire, the hide is not 'tanned.' This is because the brain solution is merely a source of amino acids, aka emulsified oils. While the amino acids do bond to the skin fibers at a molecular level, the oils are only coating the fibers to lubricate and soften them. For this tan to be true, you have to completely bind the fibers and oils in such a way that they are insoluble in water and won't wash out, while also making the skin resistant to bacterial and fungal decomposition. This is where the smoke comes in! Wood smoke is made up of many different chemical compounds, including numerous forms of formaldehyde. The most abundant of which will be glutaraldehyde gas which binds to the lubricated skin fibers on a molecular level, changing it to leather.

This will result in a waterproof, albeit primitive, true tan- the very same used by native peoples for thousands of years.

General Preservatives

Some methods of home tanning you will find aren't actually methods of 'tanning' at all, but really only a preservative. These include pure alcohol and alcohol/turpentine soaking, salt/alum mixture, egg yolk, alcohol/glycerine, salt drying or 'curing,' and others. While these will work fine to preserve a skin, they are not a true tan and do not result in viable leather. Be wary of 'cheap' tanning methods found on the internet. If they only consist of a drying agent (salt/borax) and emulsified oils (egg yolks, brains, soap) and does not include smoking the hide, it's not a tan.

Modern Tanning

Today, modern tanning usually takes form in three basic steps which alter the skin's structure; salting, pickling, tanning. The salting step is intended to 'draw out natural fluids such as lymph, tighten the fur, and hinder bacterial growth.' However, I never salt dry my skins. NEVER. Why? Because I think it's a waste of salt, AND because I find that you risk slip in your hide by waiting for it to salt dry before pickling. If you can't get it into a pickle right away, by all means salt it. But if I'm in the studio and it can go right into the pickle solution, in it goes. In fact, I get better results doing this than re hydrating dried or salted hides to tan. For me salting is only a means of storage for a skin, I never do it as a step in tanning.

Next is the pickle. This part is, in my opinion, the most important step in tanning (even above the actual tan!) The pickle will consist of some kind of acidic agent to bring the solution down to 1-2pH range and a ton of salt. For me, 1lb of salt per gallon or a little less if a part of the skin has dried out due to being in the freezer or being out too long. This is also the stage where you want to degrease your hide if you are tanning something greasy such as a bear, raccoon, beaver, wolf, coyote, etc. Degreasing is paramount to a nice and long lasting finished product. Grease is your enemy, you've been destined to battle since birth (or at least, since you decided to start tanning things.) On a more serious note; grease can and will rapidly increase the rate of decay in the finished skin. This goes double if the skin is hanging out in a warm, moist climate. The natural grease will eventually sour and rot; breaking down into acids that eat away at the leather structure. The result is leather that is 'gummy' to the touch, yellowed, and weak.

Aside from degreasing, the pickle does what salting is intended to do plus some; it pulls natural fluids such as lymph from the skin, destroys fat and other globular proteins, and effectively alters the structure of the skin, readying it for tanning. In a way, it 'strips' the skin of natural fluids and proteins and leaves behind the bare fiber structure that goes on to become leather.

The tanning process is the final chemical transition the hide will undergo. Though I said previously pickling is the most important, tanning is the most chemically complex. Tanning agents vary widely but they all essentially do the same thing; The currently unstable net of fibers which make up the skin is stabilized by the tan replacing collagen compounds with complex chromium ions. These ions form a permanent bond at a molecular level with the skin, resulting in a permanent chemical change. The resulting leather will be breathable, flexible, water tolerant, strong, insect repellent, etc. Once tanning is done the skin can be oiled with an inert oil made for leather tanning to further increase softness and flexibility.

The exact tanning agent chosen will have an impact on micro variations in the resulting leather such as color, plushness, flexibility, etc etc but most agents function along the same basic principal.



There you have it! I may tweak this in the future as I experiment more with general preservatives, and try my first 'brain' tan. If you enjoyed this or have anything to add, let me know! I hope you all find this informative.