By Steven Edholm
Hey!, the Buckeye Gathering barktanning class is coming up and I have bark on the brain. This article is going to be awesome. A lot of people ask my advice on barktanning and I see the same mistakes made over and over again. I can help, because I’ve made them all too (and still sometimes do), so I know whereof I speak! So listen up fledgling barktanners, because we can save you a lot of frustration, heartbreak and WTF moments.
Procrastination: This is a common mistake in tanning in general. I still do it all the time, unfortunately, but I shouldn’t and you shouldn’t either. Bark tanning is more forgiving than some other types of tanning because some of the solutions the hide is put into can be preservative to a degree, but that shouldn’t be used as an excuse to keep putting off what needs doing. The solutions used in liming and tanning are not foolproof and will not preserve the skin indefinitely, so try not to use their limited preservative power as an excuse for procrastination. good luck with that.
Using crappy hides: For some reason, people tend to pick some crappy hide for bark tanning. I don’t like to start any tanning project with a crappy hide. It’s too much work to waste on something which can’t be better than the material which you are starting with in the first place. If crappy hide is all you have and you want to experiment with bark tanning, working with just a small piece of it can be a great learning experience. And in general, don't be afraid to "round out" scrappy skins, meaning trim off the rough stuff and tag ends, before tanning. I also don't think it's a great idea to start with a really large hide. Actually, squirrels are great and make a great starter project, and really nice leather.
Leaving in the lime or buck too long: Leaving the skin in lime or a bucking solution too long is not uncommon. The skin can stay in for quite some time and come out Ok, but try to leave it in for a reason other than blatant procrastination! This issue is dependent somewhat on the strength of the solution. Although long liming is sometimes used intentionally, and sometimes in weak lime, generally you can process the skin as soon as the hair slips out easily. Overly long liming can weaken the skin and damage the grain.
Failing to de-lime adequately: Residual lime in the skin can cause brittleness and dark coloration. Rinse the skin thoroughly many times, and scrape over it on both sides between soakings. Re-scraping to push out lime and dissolved tissue is called scudding. You can finish with bating or drenching (soaking in poop or fermenting bran respectively, but that's another story), or at least rinse with a splash of vinegar in water before tanning begins.
Using weak-ass material to make the solution: It takes quite a bit of tannin to finish out a full skin from a medium sized animal, let alone something large like an elk or cattle skin. There are tannins everywhere. They are in most plants to some degree. Finding sources rich enough, or abundant enough, to make good tanning solutions and finish your project is less common. Don't use, old dead bark or dead leaves. You need leaves or bark that have been gathered when fresh, and have not been rained on for a season, or worse. Keep your eyes out for freshly fallen trees and get the bark when you can, storing it for later. It is possible to use weak-ass materials, but it is not practical, nor very fun, and the results are likely to be disappointing. In most cases, older trees have bark that contains more tannins than younger trees. Stripping saplings may work, but be prepared to do a lot of it! When you get that good material, chip it up fine. Boiling large pieces is another common mistake. You just can't tan an elk skin with some big chunks of old dead pine bark floating in a tub... not gonna happen.
Making the tanning solution too weak: This problem can happen for numerous reasons, some already covered above. Many people are so terrified of case hardening, that they start with a very weak solution and then finally end up with a solution that isn’t even strong enough for a good starter. The skin can be put into a pretty strong tea in the beginning without adverse effects. It can also be brought up in strength very quickly once the skin is partly tanned. For instance, you can go from weak to medium over the course of a day and have the skin in a fairly strong solution on day two. Case hardening is not common and in my experience must require a verystrong solution. I’m not even entirely sure I’ve even ever seen it at all! I just threw some squirrel skins into a full strength tanoak tea and they came out soft and beautiful. (full strength meaning shredded tanoak bark just covered with water and boiled for hours, like the picture below.)
Not strengthening the solution often enough during tanning: This is the most common mistake. The skin will use up tannins very quickly in the beginning. The process slows somewhat until the skin is struck all the way through, but it doesn’t slow down that much unless the skin is thick (think big animals like cattle). If the tan is agitated, the skin will tan quickly and the solution can be strengthened frequently to keep the process moving along. The typical beginner scenario is to put the skin in a very weak solution to start with, and then just leave it there until the solution becomes completely used up, which can take only a day, or even just a few hours. If the solution is not strong enough, the skin will begin to rot. Add concentrate frequently. If you are using materials which are poor in tannins, you will need a lot of the stuff to tan a skin (a good reason to do smaller experiments before moving on to full skins). Don’t judge by how much material you are using, judge by the strength of the solution and how the color is progressing through the skin. Judging solution strengths is difficult and has to be learned by experience for the specific materials you are using, but I also just don't think it matters that much unless it's too weak, which will be fairly obvious with a little experience. From what I hear from other people, and judging by my own experience, I’d say that a rule for beginners might be that if you think it’s strong enough, it could probably be a lot stronger. After the color reaches the center of the skin, most of the tannin binding sites are taken, and the fiber takes up the solution only very slowly.
Not moving the skin enough: This mistake is probably most important to avoid during the tanning phase, but it applies to many of the processes, such as rinsing out salt, liming, de-liming and tanning. Any time a skin is put into a solution, stretch it over and move it around to be sure it is soaked all the way up in all areas. Several visits may be necessary if the skin is not well soaked up to begin with. Air bubbles trapped in the skin can also be an issue. Many beginners stuff skins into a bucket or vat and just leave them. The skins must have solutions contact all surfaces to be processed evenly. It’s okay to fold or wad hides into containers, but there should be adequate room, and the skins should be stirred several times a day for the first few days and then occasionally until finished. If not, they will not tan evenly and can finish uneven in color. A good strategy for small containers is to remove the skins and put them back folded differently each time. Just do it often enough.
Drying the skin without oiling: This practice usually leads to brittle leather and cracking grain. It is best to oil or fat-liquor the skin once it is tanned, and before it is dried out. Otherwise the grain is generally brittle and liable to crack on bending. Oil functions somewhat like moisture does in living skin, providing lubrication for the fibers and engendering suppleness.
Bad water: Water with iron can make skins dark and brittle. If you have to use high iron water, try to keep the time the skins are in the water to a minimum. If you have very hard water,or especially if it contains iron, consider collecting rainwater for liming and bark solutions. It is difficult to collect enough rain water for rinsing processes however.
Whelp, there are of course a lot more details to fill in but, given a basic working knowledge of tanning, that's actually most of the wisdom you need to know to successfully barktan skins! If you know someone dabbling in barktanning, send them this post. We rely mostly on word of mouth to get people here. Please let us hear your experiences and experiments in the comments section. Hopefully we'll be adding Barktanning to the Paleotechnics class list sometime in the near future!