Basic Information
A Tannery is a secondary industry business that tans hides. It's the building where a Tanner converts animal hide into usable leather. It's likely to be a disgusting and dangerous location, which makes it great for fight scenes or injecting some lurid color into your RPG campaign.
Tanneries are a very foul and nasty place to visit, especially in the pre-modern era. First you've got your piles of hides and skins, which are usually acquired (fresh or pre-dried) from a knacker or slaughterhouse, but in some cases may be butchered locally in an adjoining building or yard.
To turn them into leather, these hides need to be chemically treated in a variety of ways, such as by brining, pickling and/or by soaking in acid. One of the more popular acids for the process was traditionally uric acid. The inside of a typical tannery of the Medieval era (or even the Old West) includes several large tubs or vats of stale urine. In addition, you might find solutions of feces and water, and/or brains1 and water. Honestly. Another acid bath option is sulfuric acid. There's also the dyes to color the leather, and whatever solvents are needed to keep those dyes in a liquid state. The butchered hides are soaked in these disgusting solutions for days on end, in particular sequences based on the desired qualities of the leather.
Then there's the quicklime. It's a nasty caustic chemical that burns and dissolves flesh. It's highly reactive to water, but that's kinda the point. So there'll be a dry area for storing it, and quite possibly a vat full of fat-burning nastiness sitting in solution. Depending on the size of the business and available local resources, the tannery may have it's own on-site limeburner (and all the dangers that entails), or they may have milk of lime shipped in.
These various stinky solutions are often stored in pits or ground-level tubs, because one part of the process involved stirring them up and beating them for a while. This was sometimes done by having your young apprentices climb into the poop-tank and stomp on everything bare-footed. So a large part of the building is a maze or grid of narrow little walkways over and between pits full of stuff you really don't want to land in.
Between soakings, the hides may hang to dry, or sit in piles on the ground. They may be dusted with, or packed in, salt. Some forms of leather required smoking, so you may have a large firepit on the premises. If so, there's probably a large supply of "punky" (which is to say "rotting") wood on hand as well, because the best leather-curing smoke comes from slowly burning rotted wood. Hide scraps leftover from tanning can be boiled to make glue, so there could be a boiler or a big tub of sticky on hand.
The tannery is likely to be in close contact with the local tallow boilers - who use other forms of slaughterhouse waste - and the gong-farmers/nightsoil men who supply the buckets of faeces and urine for the tanning pits. "Pure-pickers" were a specialised sub-trade who collected dog turds from the streets for the tanning industry - presumably a contract with a local Master of hounds (or at least one of his kennel men) would not be out of the question given that they are liable to have a plentiful supply of dog turds to dispose of on a daily basis. Competition with parchment makers may also occur over the finer grades of skins.
All this smelly and dangerous material often lead to laws or social expectations that tanneries would only be built on the outskirts of communities.
Sources
Game and Story Use
- Great place for a fight scene with seriously dangerous terrain.
- A chase scene through a slum or industrial district might involve a risky or surprising detour across the floors and pits of a tannery.
- A job at a tannery might be a good backstory for a character with useful crafting skills but odious personal habits.
- All those acids make it a great place for disposal of human corpses. The local mafia (or other criminal) might invest in the tannery for that reason.
- At the right sort of tannery (or the wrong sort) tanning of human, or other sapient, leather might be standard business.
- A chemical spill or foul odor at a crime scene may lead the players to suspect the involvement of a tanner.
- Tanners are also reasonably likely to have work related sores and other skin conditions that may leave evidence.
- Now imagine how nasty a place you need to tan dragonskin or other hides of resistant creatures.
- A lot of people will need ritual purification after going into one of these places - many real world religious traditions regard such things as spiritually unclean and polluting and it would be entirely reasonably for a fantasy one to do so.
- If your game has any rules for disease, you'll want to dig them out for anyone who goes near here, especially with an open wound.