For many of you seasoned crafters, this might be redundant information. But for the novice amongst us, knowing the basics of leather making can make a big difference in their material-related decisions. I have thrown in some Italian words just for fun.
How Leather is Tanned (“Concia della Pelle”)
Leather is a complex biochemical and organic material that has historically been tanned using natural tannins, transforming raw hides into durable, workable leather. The two most common methods are:
Vegetable Tanning (“Concia al Vegetale”)
This is one of the oldest tanning methods, relying on natural tannins extracted from tree bark, leaves, and fruits. The process takes weeks or even months, but the result is a firm, durable leather that develops a rich patina over time. Oils and waxes are applied externally, depending on the article being produced. A hot plating is also employed to bring out oils to the top face of the leather to achieve shiny glossy look. Waxes can be applied to give leathers a frosty look and is a feature in some articles like “Ghost”. The waxes can be burnished off or left to gradually wear off as patina develops. Very bright colors are hard to achieve or sustain on vegetable tanned leathers. Colors are also likely to fade or darken to warm earthy colors, depending on use and exposure to sunlight. But that is the natural beauty and a unique selling point of vegetable tanned leather used for leather goods. Due to the manufacturing time and associated costs involved (veg tan in many weeks versus chrome-tan in a few days), vegetable tanned leathers are more expensive than chrome-tanned leathers.
- Best for: Belts, wallets, saddlery, and traditional leather goods.
- Color & Finish: Starts with warm, earthy tones that darken with age.
Chrome Tanning (“Concia al Cromo”)
A relatively more modern method, chrome tanning uses chemistry where chromium salts are introduced to speed up the tanning process, producing a softer and more flexible leather. This method strips away natural fats and significantly transforms the underlying fiber tissue but also allows for a wider range of colors and finishes on the grain surface.
- Best for: Handbags, upholstery, and fashion accessories.
- Color & Finish: Smooth and even, with better resistance to water and wear.
Combination Tanning (“Concia Mista”) or Re-tanned Leather
This hybrid method blends vegetable and chrome tanning, balancing durability with flexibility or softness. In re-tanning, “wet blue” crust (the light blue color is the result of chromium chloride in chrome tanning) can then be vegetable tanned to selective add back characteristics, depending on the end use desired. Chrome-tanned leathers are commonly used for high-end leather goods that require both structure and flexibility and vibrant colors that are usually not achieved in vegetable tanning. Recently though, due to environmental impact of hexavalent chromium salts, most countries have imposed severe restrictions on tanneries to treat their tannery waste. Due to the economics of complying with regulations, many tanneries are moving to severely limit chrome in their process, non-chrome alternatives, or move to metal-free tanning methods.
- Best for: Luxury handbags, premium footwear, and durable accessories.
- Color & Finish: A balance between firm and supple, with deep color penetration.
… to be continued in Part 3 where we discuss dyeing, finishing, and cuts of leather.