How leather is tanned: Billy Tannery goat leather

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Although I’ve visited many workshops and factories over the years, I’ve never been to a tannery (a trip to Barker’s is way overdue).

It was with particular interest, therefore, that I went to see the tiny operation set up by Jack Millington (below) in the stables of his parents’ farm.

Jack also has a nice story. At one point a couple of years ago, he became interested in the skins from his father’s goats, which were simply thrown away once the animals died.

Jack began to wonder if there was a use for this waste product – whether they could be tanned or in some other way re-used.

That led to conversations with nearby Northampton University, which due its proximity to England’s shoe industry, has a lot of leather expertise.

Many people were keen to help. It turned out one man, who specialised in repairing and supplying parts to tanneries, had a couple of small drums sitting in his yard going spare. Paul Evans at Northampton University was particularly keen to help Jack get this off the ground, and began explaining how it would be done.

In exploring markets for the leather, Jack also came across other goat farms that were bigger and had larger quantities of skins going to waste.

Jack and his father got the two drums into their old stable (below - they barely fit) and started experimenting with tanning the waste skins – following a process Paul had set out in a colour-coordinated spreadsheet.

Today, Millington Sr and Jr have pretty much got the process down. They’re producing tanned goat leather and making a few finished goods – under the brand Billy Tannery.

The tanning process comprises several stages, some here and elsewhere, and in different drums.

The first takes place off-site. The skins have to go through a fleshing machine, to take off all the fat and the salts that are often used to stop them going off. This is done at Northampton (a new one would cost thousands).

In general, by the way, the stages of the tanning process are all largely aiming to remove anything in or on the skin that could off in the future – and replace it with things that can’t.

The first stage on the farm is liming. The skins are soaked in an alkaline lime solution to remove any hair. This happens overnight, with the drum turning for five minutes in every hour.

Liming causes the skins to swell up and whiten. The lime is then drained (all liquids are kept outside the stable and re-used, which is nice in terms of sustainability).

Then there's de-liming, where a weaker alkali is used to remove the lime, followed by bating.

Bating is the process that used to make tanneries very unpopular. It uses an enzyme solution, which you can make from most animal products, including faeces.

Today you can buy an enzyme solution and there is only a faint ammonia smell.

At this point, the skins are moved to the other drum, for pickling.

This brings the acidity down even further – and Jack will often test the skins for their pH level (using those old litmus-paper strips you may remember from chemistry lessons - above).

Other tests during the tanning include slicing open the skin, to see how far something like iron has penetrated into the middle. Anything left untouched could eventually go off.

These four stages are sometimes referred to as the ‘beamhouse’. What comes next is the actual tanning.

This is where the tanner decides to make either vegetable-tanned or chromium-tanned leather. The vast majority of the world’s leather is chrome tanned, but veg tanning creates a richer, more natural colour and keeps more of the character of the leather.

Veg tanning can be done with a huge array of natural materials. The best leather soles for shoes, for example, use oak bark – mostly at Barker’s in the UK, which also grows its own trees for the purpose.

Jack tried out various materials for the tanning, such as chestnut, but found that mimosa bark was generally best for their goat skins. This he gets in powder form (below) from South Africa.

The tanning is done overnight, with the skins soaking in a solution of this powder and water, turning as slowly as possible.

There is a final stage – fixing – using a mild acid, an anti-mould solution and anti-iron together (veg-tan leather is particularly prone to stains from iron). Then the skins are washed and taken out to dry.

Jack is taking out the washed skins below, and putting them on a wooden horse to drip dry.

One of the hardest aspects of tanning like this, in a small space, is controlling humidity and temperature. Tanning agents work best at particular temperatures, and keeping them there through the winter is hard.

In England, drying is often hard too. Luckily England is currently going through one of its warmest periods for decades, but drying in typical wet weather is tough.

The skins are pegged onto vertical racks – below – in a room with a heater and a dehumidifier.

The pegs are there not to stretch the skins, by the way, but to stop them shrinking as they dry. Stretching would be something done to create a thinner leather, such as vellum.

From here, these dry and pale-tan skins are sent to a finisher – Blenkinsop’s, about 45 minutes away.

They may do a bit more tanning, but they specialise in hand-painting colours, adding prints (a lot of fake exotics use goat to stamp on), splitting the skin for a particular thickness, and finishing the suede side if that will be on the outside.

The leather that results is something we can now recognise from our bags and shoes: the mid-brown you can see below.

Jack is justly proud of the end result, although unfortunately his parents have also just moved to a new farm, so this whole tanning operation will have to be moved too.

At least this time they’ll know what they’re getting themselves in for.

As mentioned, Billy Tannery is in the first stages of developing its own products, which can be seen on its site and in person in the window of the Temper restaurant in London’s Soho.

I’m particularly interested in using the leather for outerwear, and we’re currently working on a plan to tan something in a desired colour and thickness, and then work with Cromford Leather to make it into a bespoke piece.

A leather jacket, from farm to finish.

Many thanks to Jack for his hospitality (and his Mum for the great local pub recommendation).

Photography: James Munro