Understanding Leather Tanning

The word leather describes a widely diverse range of materials, made through a equally diverse set of processes, all collectively called Tanning. In general and in brief, tanning involves the following steps.

1. An animal is slaughtered and skinned.

   
   

2. The hide is scraped and washed clean.

   
   

3. The hide is soaked in a series of chemical baths and washes.

   
   

4. The hide is dried, graded, and packed for shipping.

The type of leather you get will depend on which chemicals you used to process the hide in step 3.

What is Vegetable Tanned Leather

Vegetable Tanning is one of the oldest ways to make leather. It uses extracts from tree bark and other plants to tan the hide, the "vegetable" in "vegetable tanned."

All of my goods are constructed primarily from this type of leather. It has many unique properties that allow it to be shaped, carved, and dyed freely. It is almost like clay when you get the moisture content just right, and it is these unique properties that make my designs possible. As malleable as it is when it is wet, vegetable tanned leather (veg tan) is quite firm to the touch when it dries. A piece can stand up when held upright without flopping over. It would not be suitable for garments or upholstery, but it makes for excellent saddlery, belts, boots, cases, and many other useful items.

It takes at least two months in the tanning solution to fully tan a hide with this method. A glacial pace in the tanning industry.

Because these the tanning solution is essentially a big, bitter cup of tea, it is the most environmentally friendly form of tanning, especially compared to the next tanning method we will discuss.

What is Chrome Tanned Leather

When you replace those plant extracts in the vat with Chromium salts, you get chrome tanned leather instead.

Chrome tanned leather makes up about 90% of the leather produced worldwide. Most modern garment and upholstery leathers will be chrome tanned. This is the much softer and more flexible material everyone is familiar with.

Soft leathers like Chrome tan behave so differently from the harder vegetable tanned leathers working them is considered two different skillsets entirely, requiring different tools and techniques to construct and finish goods.

Chrome tanned leather often, but not always, has its grain "corrected" That is to say, all the scars, stretch marks and other natural imperfections of the animal hide have been sanded off and the leather has been artificially resurfaced to provide a blemish free product. Doing so increases the aesthetic quality of the leather but decreases the utility quality of the leather, weakening it substantially. Doing this to vegetable tanned leather would ruin all the unique working properties I mentioned earlier, and it is not done.

A chrome tanned hide can be produced in a single day, compared to the months required for veg tan. For this reason it can be much cheaper than veg tan on the lower end, though there are still very nice, very leathers made this way.

The chromium salts used in tanning are much more complex to dispose of properly. Ideally, they are processed into less harmful components first, but the reality is that most of the leather tanning industry has moved to countries with less strict environmental regulations which allow them to pollute with impunity.

Even worse, the cheapest chrome tan leathers can be a danger to the end user. If the process was especially rushed, the chromium may not have been completely washed out of the leather, meaning this highly toxic chemical are introduced to your home.

Other Methods

Rawhide making is an even older process than vegetable tanning, and produces something much, much harder. This is primarily used today for drum-heads and dog chew toys.

Aldehyde tanning is a similar process to Chrome tanning, but much less popular. It uses different chemicals to a similar end. It is more complex but yields a chromium free product. It sees its widest use in automotive upholstery

Brain tanning is no longer practiced on an industrial scale and is only seen today as a historical novelty and as a part of traditional bushcraft. This method of tanning uses the brains of an animal to tan the hide and produces a softer leather that was much more similar to modern chrome tanned leathers than anything else available at the time.