HOW TO PLAN YOUR BARK-LIQUORING SCHEDULE
The way I teach is influenced from my teachers. Not hide tanning teachers, but teachers of other modalities who have imparted a decolonial lens to learning. Part of this means: I get people to do things for themselves from the start.
Following a manual can feel like learning, but it's actually not learning - it's anticipating. Actual learning comes from the body, in the doing of a thing.
If you've tried bark-tanning, you might have followed a schedule of “bark-liquoring” to guarantee your hide turns to leather properly. You might know some of of the reasons why the schedule is structured like it is. And you might not know enough of the principles of hide tanning to make your own schedule, to adapt when life interrupts your hide work, and to scale up or down on differently sized hides.
So here's what to know to make your own bark-liquoring schedule.
HOW TO PLAN YOUR OWN BARK-LIQUORING SCHEDULE
Real Quick: what is bark-liquor?
Bark-liquor is a liquid solution in which we put hides to tan them into leather. Bark-liquor is a concentrated tea of any plant that has high enough tannins content and the right type of tannins to tan leather.
Bark-liquor is only used in the “bark-tanning” or “veg tanning” methods. They are the same method, but you usually see “veg tanning” used incorrectly in commercial leathers that have ingredients beyond tannins, so in natural hide tanning we've adjusted and just say "bark-tanning." And - you know I love combo-tanning, so I will add that you can take any smoke-tanned or mineral-tanned hide and put it in a bark-liquor as well, for a combo-tan.
Day One
This is the most important day. The hide is at its most vulnerable: it is just a raw piece of skin right now, zero preservatives in the hide itself and lots of moisture all up in it.
Pretty soon, the hide will start absorbing tannins, which will preserve as they tan (to tan is actually a chemical transformation, the hide is preserved in the meantime while tanning takes place)
The hide is also at its most receptive right now. It's like a big concert venue with no people in it. A bunch of people (the tannins) want to get into this venue.
You are the ticket-checker. Your job is to get people (tannins) into the venue as quickly as possible, in an orderly manner
This is why we heat up bark-liquor before submerging a hide = quick movement
This is why we dilute bark-liquor before submerging a hide = orderly manner
Then you go from from ticket checker to usher:
This is why we stir the hide for 20-30 minutes as soon as the hide goes into the bark liquor = getting everyone (tannins) into their places
Now you get to plan + adapt: did you start bark-liquoring in the morning, are you going to stir once an hour all day? Or did you start in the evening, are you going to let it rest overnight and then commit to some active stirring first thing in the morning?
As long as you know that the first 24 hours are the most important, you can plan your hide time + the rest of your day accordingly.
Day Two
Since the hide was at its most receptive yesterday, it has now absorbed the most tannins in a single day that it ever will. Most of the concert goers got into the venue when doors opened. Not a late crowd.
The hide is still vulnerable, because it's only partially tanned. Very partially. Most of it is still raw skin.
So today, you're going to strengthen the bark-liquor. You want to ensure more people get into the venue, you need to sell this place out. You are, um, a promoter now. You will go back and forth between usher and promoter from here on out.
Heat up more bark-liquor (which you've already made, see last HTOTM) and pour it into your current solution. Sit there and stir, getting every tannin into its right place.
It does not matter what time of day or how many gallons of bark-liquor or the precise timing of stirring. What matters is understanding the principle so you can learn by doing.
Days Three to Ten+
Now the hide is really looking like leather. You are going about your life, and the hide is on the back of your mind.
If you want the hide to turn to leather faster, you will spend more time each day stirring it. And you will keep the bark-liquor very warm.
If you want the hide to turn to leather slower, you will ideally still stir it once a day but maybe only for a few seconds instead of ten minutes. You will not bother worrying about how warm the bark liquor is (it needs to be above 15 C for tannins to move, but that's it).
Now you have to go out of town. You get to decide: do I ask a friend to stir my hide, or do I let it sit and absorb tannins slowly? If it's the latter, you'll weigh your hide down with a non-mineralized rock or some other weight + expect to see a mould bloom on the bark-liquor surface when you're home. You know that the hide is safely submerged + once you start stirring again the mould spores won't have a chance to form, so you skim it off like a sauerkraut bloom and move on.
Around Day 5, you'll scud your hide. Scudding is a perfect moment to strengthen the bark-liquor + spend extra time stirring when the hide goes into this more concentrated batch. Knowing this, you schedule your scudding day when you have time stir. It might be day 4, it might be day 7. The important thing is not the exact day, it's the action of supporting the tannins going into the hide. Promoter and usher, that's you :)
The Last Couple Days
Now the hide has absorbed close to all the tannins it can.
The concert goers (tannins) are moving slowly to their seats, it's hard to find a spot when the room is so crowded. Knowing this, you don't assume your bark-liquor is advancing as quickly now as it did on Day 1 or 2.
Knowing this, you do one final bark-liquor strengthening. This is the act to send the hide home; for me, it's often a highly concentrated bark liquor (in Hide Club we are doing this with our goat skins on Day 8, which is next Tuesday).
There might be another three days or another five days after this final bark-liquoring strengthening. We add it to give the hide as much osmotic pressure as possible to really push tannins into the last open seats available.
I wouldn't add this concentrate, say, on the second-to-last day. Then I'm just going to have a lot of un-absorbed tannins in the solution. A lot of people standing around the concert venue, not in the seats, making a sticky mess.
The Spent Solution
After a bark-liquor has tanned a hide once, it is a spent solution.
Literally the slowest tannins didn't make it into the hide
Give these a chance for the next hide, by making this spent solution your starting bark-liquor
The schedule you come up with will create a spent solution that is more or less high in tannins. I tend to walk away with highly tannin spent solutions. I'll toss a couple small hides in it after tanning a big hide, and I do very little labour to get those smaller hides tanned. Other people will have spent solutions of lower tannin content, say if they did not do a final strengthening but rather let their hide slowly, slowly absorb tannins in its final days. Those tanners will have a weaker solution, possibly one that they want to use as a liquid base for extracting more tannins rather than a starting base for a new hide.
You get to choose - and this might not be a conscious choice. It probably won't be. it'll be the habits your form, your body leading the way, that creates system you find yourself in and barely realized you're the usher of.