Bark Tanning – How To
Tanning animal skins and furs is a very satisfying craft to develop and there are many processes/ methods you can use to preserve these natural materials.
A fairly straight forwards approach is to soak your animal skin or fur in vegetable tannins – you can boil almost any tree bark to create a dark brown ‘tea’ with which to submerge the hide in.
The type of bark you use for the tannins and whether you boil or simply cold soak the bark will produce different types of tannin that will have different effects on the skins you are trying to tan.
There are a great many factors affecting the resulting products of veg tan for example:
- The type of hide you soak
- The length of time the hides are left to soak
- Cold soak or boiled tannins
- Type of tree bark used
- How/ if you then go about softening the resulting leather
- Whether the grain is left on a hide or removed
The fact that you can produce a range of colours and a variety of thicknesses and flexibilities gives you a huge selection of material properties to aim for with a certain finished product in mind.
Think of the hard, thick and very inflexible nature of boiled leather armour as compared to the supple soft and water-resistant leather required for water resistant footwear as an example of how different veg tanned products can be.
The ability to preserve animal skins and furs using tannins is a highly useful skill in bushcraft and is highlighted historically by just how many industries relied on leather products in by gone times. Some examples of how leather was and still is put to practical use:
- Saddles, straps and horse-riding rigging
- Boots, footwear, hats and gloves
- Bags and quivers
- Armour and sheaths
- Seat covers
- Bellows for forges
In a world pre plastics and synthetic materials the skins of large domestic animals such as horses and cows were highly valued and our tanning industry here in the UK was booming on an industrial scale.
The timber from our Oak woodlands may have been destined for the Navy and construction but the bark that was peeled from the logs was sent to the tanneries where it could be processed to extract the precious tannins used in converting green hides into tough durable leathers.
A simple home trial of tanning animal hides using tree bark couldn’t be more straight forwards with very little time on your part and almost no expense in equipment and materials required.
If you want to attempt tanning a hide with tree bark I’d suggest opting for something very thin that will absorb the tannins fairly rapidly and thoroughly – a big pit fall in this type of tannin is ensuring that the tannins ‘travel’ right the way through the hide and don’t simply bond to the outer surfaces which could then lead to the centre of the hide rotting over time.
So you might choose a rabbit hide for example – these are notoriously thin skins and some care should be taken in the skinning and scraping clean the inside surface to remove any meat or fat.
You should know that tanning furs in this way will stain the fur a dark colour so if you are looking to preserve the beautiful snow-white pelage of a mountain or snow shoe hare for example then you should seek an alternative method!
You will need access to some tree bark – any type will do but Oak and Sweet Chestnut are favourites for me seemingly providing endless amounts of dark tannins when boiled up. Talk to tree surgeons if you are struggling for materials and see if they have any branches from jobs that you can salvage pre wood shredder.
You’ll need a large pan to put the bark into (aim for half a carrier bags worth) and fill the pan with water. Ideally this boiling should be done outdoors, but indoors works fine provided you can vent the steam as it boils.
Aim to simmer the bark for an hour to extract the dark liquid you’ll use to tan the hide. This is your concentrated stock solution. Allow it to cool and DO NOT pour it onto your hide whilst hot as this will ruin the skin.
Next you are going to dilute the concentrate down to half strength, so measure the volume, pour half into a plastic container where you will tan the skin and make the volume back up with fresh water. You will keep the left-over concentrate to top up the tannins on a daily basis until the hide is finished.
Submerge your hide in the diluted tannins in a Tupperware container or similar and agitate the solution regularly for the first day. For the following 14 days or so all you are required to do is add a cups worth of the concentrate tannins (you may need to boil up more batches of concentrate) each day and swirl the hide round in solution.
You will see the concentrate become paler each day as the tannins are absorbed and locked into the hide so you should darken the solution as necessary to make more tannins available. Two weeks of this treatment is more than enough to preserve rabbit furs and Salmon skins for example.
Once your hide has taken on a dark colour you can remove it from the bath and allow it to dry so that it is only a little damp. At this point you would rub oils all over it – vegetable oil is cheap and fine for this. Let the hide sit flat covered in oils (avoid the fur side if dealing with rabbit) then after a few hours stretch and pull the hide gently.
A lot of the oils will simply pour off, but the idea is to keep applying more coatings of oil, leave the hide to absorb and then repeat the stretching process. With 2 or 3 treatments of oil you can then continue working the hide until it dries and should remain pleasantly flexible.
Furs will take much longer to treat this way as you can only oil and work from one side and the fur will slow down the drying time.
- Skin carefully
- Scrape the flesh side clean
- Boil tree bark
- Dilute stock solution to half strength by pouring off half the volume and topping back up to full volume with water
- Retain the other half concentrate solution
- Submerge hide in COOL diluted tannin bath
- Watch for hide to darken and solution to pale
- Add 1 cup concentrate per day for 2 weeks
- Remove hide and allow to dry to damp feel
- Work oils into hide
- Stretch and soften
If you’re inspired to join us in the woods to learn more about these wonderful natural resources, why not join us on one of these upcoming courses:
Basketry and Bark Work Weekend – 12 – 14 July 2019, Oxfordshire
Fur Trade Weekend – 19 – 21 July 2019, Oxfordshire
Woodland Wayer 2-Year Course – Starting 14 – 16 February 2020, Oxfordshire