Tanning and leather
Turn raw hide into a material that does not rot.
Everything for this step
- Field guide
- Livestock husbandry → 6 sections Hunting and trapping → 5 sections
- Builds
- Double-chamber bellows
- Reference sheets
- 1 sheet in Hunting and trapping
- Sciences it rests on
- Chemistry
- Track
- Fibres, textiles and leather, level 2 of 2
Why this matters
Leather is your belting, harness, footwear, bellows, hinges, buckets and armour for the next several tiers. Bellows in particular are the gate to metallurgy — you cannot force air into a furnace without them.
The shape of it
- Flesh and dehair. Scrape all flesh and fat off immediately; soak in a lime or wood-ash solution for days until the hair slips, then scrape it off and rinse thoroughly.
- Bark tanning is the durable route: crush tannin-rich bark (oak, hemlock, chestnut, wattle) and steep it in water to make liquor. Move hides through progressively stronger liquors over weeks to months. Rushing it tans the outside and leaves a raw core that will rot.
- Brain tanning is the fast route: the animal's own brain emulsion worked into a scraped hide, then worked constantly while drying, then smoked. Produces soft, breathable leather; smoking is what stops it going stiff when wet.
- Rawhide — dehaired, dried, untanned — is not leather but is enormously useful: lashings that shrink tight as they dry, drum heads, and hard fittings.
- Oil and finish the tanned leather with tallow or fish oil to keep it flexible.
- Site the tannery downwind and downstream of everything. It stinks, and the liquors are foul.
- Make the bellows early. Two boards, a leather gusset and two valves — and suddenly smelting is possible.
Doing it, step by step
The summary above says what has to happen. This says how, with the numbers that decide whether it works.
1 · Flesh the hide the same day, or salt it
A hide rots within a day in warm weather and cannot be recovered. Start fleshing within hours of skinning.
Lay it over a smooth log or beam, flesh side up, and scrape off every scrap of meat, fat and membrane with a dull-edged fleshing tool pushed away from you. If tanning cannot start within a day, rub salt thickly into the flesh side, into every fold and edge, fold it flesh-to-flesh, and keep it cool.
2 · Dehair in lime or ash, then remove every trace of the alkali
Soak the fleshed hide in a slurry of slaked lime — or strong wood-ash water — stirring daily. Test for hair slip every day from day 3: tug hair from a thick part. Ready when it comes out easily, usually within 3–10 days. Scrape the hair and the grain layer off with a blunt tool.
Then delime: rinse thoroughly, and soak in several changes of water, finishing with a weak acid bath — a little vinegar, or fermented bran water. Any lime left in the hide stops tanning from penetrating and leaves it brittle.
3 · Bark-tan in progressively stronger liquors
Oak, chestnut, hemlock and wattle bark are rich in tannin. Grind the bark, steep it in water — warm, not hot, since heat darkens the leather — for days, and draw off the liquor.
Start the hide in weak, used liquor and move it to stronger liquors over weeks. A hide put straight into strong liquor tans on the surface and seals, leaving the centre raw — it looks finished and rots from inside later. Allow weeks for light hides and 6–12 months for thick sole leather, turning and handling the hides regularly.
4 · Brain-tan for soft leather, and always smoke it
The fast route. Every animal has about enough brain to tan its own hide. After dehairing, scrape off the membrane on both sides. Mash the brain into warm water to a thin emulsion and work it into the hide until saturated, then wring it out.
Stretch and work it constantly while it dries — over a cable, a post, a frame — for hours, until it is completely dry and soft. Stop early and it dries stiff. Then smoke both sides over a smouldering fire of punky rotten wood, no flame, until evenly coloured. Smoking is what stops it going rigid the first time it gets wet.
5 · Use rawhide where you want something that shrinks tight
Rawhide — dehaired, fleshed, stretched and dried, not tanned — is not leather, but it is enormously useful. Cut into wet strips it binds hafts, lashings and joints and shrinks tight as it dries. It makes drum heads, hinges, containers and hard fittings.
It softens and eventually rots when kept wet, so keep it out of water once dried.
6 · Oil and finish it while it is still damp
Stuff the tanned leather while it is still slightly damp: rub in tallow, neatsfoot oil or fish oil on the flesh side and let it soak in, then work the leather over an edge as it dries. This keeps it flexible and water-resistant, and dry leather that was never oiled cracks.
Re-oil working leather — harness, belts, boots, bellows — every few months and whenever it starts to look pale and dry.
7 · Site the tannery downstream and downwind — and refuse suspect hides
Liquors, lime and flesh waste are foul and they poison water. Put the tannery downwind of everything, downstream of every water intake, and at least 30 m from any water source, with waste liquors going to a soakaway or pit, not a stream.
Keep a record of where each hide came from.
8 · Make the bellows early
Two shaped boards, a leather gusset nailed between them, and two flap valves — one in the lower board to draw air in, one at the nozzle end to stop it being drawn back from the fire. A pair of single bellows worked alternately, or one double-chambered bellows, gives a continuous blast.
That blast is what makes smelting and smithing possible. See the bellows build for dimensions.
Build it
Dimensioned drawings, bills of materials and construction procedures for the things this step asks for.