TL San Martín

Leather fundamentals

What is leather and what are its advantages?

Leather is one of the oldest and most durable materials known to humankind. Here is what it actually is, how it is made, and why it remains irreplaceable in footwear, leather goods and apparel.

TL San Martín technical team Updated: 2026-06-08 Español · English · Português

Leather is animal hide — usually bovine, goat or sheep — that has been tanned to turn it into a stable, flexible, rot-resistant material. Untanned, hide decomposes within hours; tanned, it lasts for decades. It is a by-product of the food industry, breathable, repairable and biodegradable, which sets it apart from petroleum-based synthetics.

What does «leather» actually mean?

«Leather» refers to animal hide once it has been tanned. Raw hide is organic tissue that rots within hours if untreated. Tanning stabilises the collagen structure of the dermis and turns it into a rot-proof material we call leather.

Every piece of leather was once a hide, but it only becomes leather after tanning. We explain the nuance in our guide on the difference between hide and leather.

Fact: leather is almost always a by-product of the meat industry. The hides that are tanned come from animals raised for food — no animal is slaughtered to produce leather.

How is leather made?

Tanning turns raw hide into finished leather in several stages:

  1. Beamhouse: the hide is cleaned and the hair and flesh removed.
  2. Tanning: the key stage. Tanning agents bond to the collagen. The most common are chromium salts (chrome tanning) or vegetable tannins. There is also chrome-free tanning.
  3. Retanning and fatliquoring: adjusts handle, body, softness and water resistance.
  4. Dyeing: adds colour through the thickness or on the surface.
  5. Finishing: gives the final look — matte, glossy, patent, nubuck, embossed, metallic — and performance.

At our tannery in Elda (Alicante, Spain) we retan, dye and finish bovine, goat and sheep leather, controlling every batch for consistent colour and handle.

Advantages of leather over synthetics

Types of leather by hide layer

TypeWhat it isTypical use
Full grainThe intact top layer, unsanded. The strongest and finest.Premium footwear & leather goods
Corrected grainGrain sanded and re-embossed to even out defects.Mass-market footwear
SplitThe lower layer of the hide, separated from the grain.Linings, suede, work footwear
PatentLeather with a high-gloss lacquer finish.Dress shoes, bags
Nubuck / suedeGrain (nubuck) or split (suede) sanded for a velvety touch.Footwear & apparel

For footwear we expand this in types of leather for footwear.

Frequently asked questions

Is leather the same as hide?

Colloquially they overlap, but technically a hide is the raw, untanned skin and leather is that same skin once tanned and finished. Every piece of leather comes from a hide, but it is only called leather after tanning.

Which animals does leather come from?

Most commonly cattle (bovine). Goat, sheep and pig are also tanned, and reptiles or fish for exotic articles. At TL San Martín we mainly finish bovine, goat and sheep leather.

Is leather sustainable?

Leather is a by-product of the meat industry: it uses hides that would otherwise be waste. It is also biodegradable and very durable. Modern chrome-free and certified tanning (such as Leather Working Group) reduces the environmental impact further.