Bark-tanned Sheepskin Rug
The Bark-tan method uses tannins from plants to tan hide (and yes! that’s the etymology of the word ‘tan’). Some important things to know about tannins:
We always use plant material fresh from a recently-harvested plant, before water has leached tannins away and before time has degraded tannins
Most tanners in North America use bark from trees, as it’s the largest single source of tannins
Tannins are then extracted from the plant material with a gentle water infusion, like a tea
We need 5-10 lbs of tannin plant material per hide, depending on the size of our hide and how efficiently we make use of the tannins
The easiest tannin for beginners is Mimosa (Acacia) extract
If you harvest your own bark, it will be variable in tannin content. Please get a “barkometre” if you work with self-harvested bark to measure tannin content.
We will dive into tannins much more in Hide Club. For now, if you want a quick primer, this file Types of Tannins is a great, simple overview of tannin classification. Tannins are divided into two, three, or sometimes four categories, depending on what qualities the classifier is prioritizing. Start here with the definitions in this file, which use the two-type classification system: hydrolyzable and condensed tannins.
If you’re harvesting bark yourself for Hide Club, you’ll need to get “the right kind” of tannins from that bark. Not all trees have the corerct polyphenols that will transform hide into leather.
Use this PDF guide from Hide Club’s bark-tanning cohort 2024. In it, there are plant monographs on verified tanning-worthy trees. It is not an exhaustive list, as there are hundreds of thousands of trees that can tan hides. But you’re likely to see the most familiar trees near you.
Do not use Western Redcedar or Black Walnut for tanning. I also recommend against using acorns and Sumac for beginners.
Tannins FOR HIDE CLUB
Hide Club is BYO-tannins: you choose which tannins you want to work with + whether you harvest them yourself or purchase them.
Deciding which tannins to work with may be a matter of meeting what’s in your local ecosystem or on the colour you want your leather to be - or simply what’s the most affordable option.
You’ll want 5-10 pounds per hide of dried tannin material per hide. If using extracts such as Mimosa or Chestnut, you can likely tan the sheep skin with just 5lbs; if using self-harvested bark, you definitely want 10 lbs.
I recommend getting more than enough tannin material for one hide - this way, if you have leftover tannin, then you can use it for your next project.
Of note: I strongly encourage beginner tanners to purchase their tannins. For anyone who is harvesting their own, please get a “barkometre” device so you can measure the tannin content of self-harvested bark.
Purchased Tannins
If you’re brand new to bark-tanning + want the simplest, fastest-acting, and most affordable purchase option, get Acacia (Mimosa) extract powder. This will turn your leather a light pink to red.
If you want all of the above qualities except a light beige leather, find ground Oak or Oak Gall powder.
If you want a brown leather, get Willow.
I recommend beginners don’t work with Sumac…not yet :)
Our recommended list of tannin suppliers:
Boundary Hide and Leather
Just a guy named Wes who buys Acacia (Mimosa) extract wholesale and sells it to other tanners
This is a great Canadian option for Mimosa (most affordable if you factor customs fees of Themazi and TT)
Email boundaryhidetanner@gmail.com
Vancouver, BC store + school of natural dyeing
Has tons of variety for tannins; higher cost
You can search their website information for details on tannins
Based in Türkiye + works directly with producers
Has tons of variety
You need to somewhat know what product you’re looking for, i.e. not all natural dyes are tannin-based
Their Oak galls, Pomegranate, and Acorn extracts will all tan hides
Based in Oregon, USA + buys Acacia (Mimosa) wholesale for re-sale + harvests their own Tanoak (Notholipocarpus) bark
You can also get extracts of Acorn and other on-again-off-again products
Great for buying large quantities at once at a reduced cost (most affordable option for Americans)
Canadians will have to pay customs duties
Harvesting Tannins
It’s most likely that to harvest tannins, you’ll be harvesting bark. A major exception is shrub Willow, which can be harvested by clipping the shoots and chipping them up finely. Another exception is Sumac, in which we use the leave - but I recommend not using Sumac as a beginner. Wait til you have some bark-tanning success before using this high-demand plant.
Bark harvesting principles + directions
A tree must be freshly fallen from a windstorm or cut by hand. Scrape the bark within 48 hours of cutting if possible.
Once rain gets to a fallen tree, the tannins leach away
The bark is stripped by hand with a drawknife or by power tool with a “log wizard” attachment for a chainsaw
Once stripped, the bark is chipped into pieces using a hatchet, typically on a piece of plywood to catch all the flying pieces
See the section “Harvesting Bark” for a video on harvesting tannins