Base elements → Materials → Organic materials

LEATHER

Table of main properties of leather

 

Property Typical Value Remarks
Density ~0.8–1.0 g/cm³ Low
Young’s modulus (E) ~0.1–0.5 GPa Very low
Tensile strength ~10–30 MPa Depends on type and treatment
Hardness (HV) Not applicable Flexible organic material
Thermal conductivity ~0.1–0.2 W/m·K Very low
Electrical conductivity Very low Insulating material
Thermal expansion High Variable depending on humidity
Melting point Not applicable Decomposes when heated
Magnetism No Non-magnetic
Corrosion resistance Good Sensitive to moisture and aging
Machinability Easy Cut, stitched, shaped

Leather is an organic material derived from processed animal hides, used in watchmaking primarily for the production of straps. Appreciated for its flexibility, comfort, and aesthetic qualities, it remains one of the most traditional and widely used solutions for wearing watches.

Over time, the use of leather has evolved under the influence of regulatory constraints, ethical considerations, and material innovations, leading to the development of new alternatives, particularly plant-based leathers.

Main Properties

Leather exhibits specific characteristics:

  • Flexibility and wearing comfort
  • Good mechanical strength (depending on type and tanning process)
  • Breathable material
  • Sensitivity to moisture and wear
  • Evolving appearance (patina)

These properties make it well suited for everyday use.

1. Traditional Leathers

  • Calfskin → the most common
  • Cowhide → robust
  • Full-grain leather → high-end

Characteristics:

  • Good durability
  • High comfort
  • Natural appearance

2. Exotic Leathers (Historically Widespread Use)

  • Alligator / crocodile
  • Lizard
  • Ostrich

Characteristics:

  • Distinctive aesthetic
  • Unique texture
  • High-end positioning

👉 Their use is now highly regulated (CITES).

The trade of certain exotic leathers is regulated by CITES (Convention on International Trade in Endangered Species).

This regulation aims to:

  • Protect endangered species
  • Regulate international trade
  • Ensure material traceability

👉 In watchmaking:

  • Alligator and crocodile leathers remain permitted under strict conditions
  • Certain exotic leathers are prohibited or heavily restricted
  • Specific documentation is required (CITES certificates)

1. Plant-Based (Alternative) Leathers

In response to ethical and environmental concerns, new materials have emerged:

  • Apple leather
  • Pineapple leather (Piñatex)
  • Grape leather
  • Cactus leather

Characteristics:

  • Non-animal origin
  • Reduced environmental impact
  • Leather-like aesthetic

2. Synthetic Materials

  • Polyurethanes (PU)
  • Technical textiles

👉 Used for:

  • Sports watches
  • Cost-effective alternatives

The main steps are:

  • Hide selection
  • Tanning (vegetable or mineral)
  • Cutting of components
  • Multi-layer assembly
  • Stitching (often saddle stitching, machine, or hand-stitched)
  • Finishing (dyeing, varnishing, embossing)

A strap can be composed of several layers:

  • Outer leather
  • Internal reinforcement (core)
  • Lining

Leather is used almost exclusively for:

Advantages

  • High comfort
  • Warm aesthetic
  • Wide variety of textures
  • Lightweight
  • Natural material
  • Develops a patina over time

Limitations

  • Sensitive to water and humidity
  • Progressive wear
  • Limited lifespan
  • Regulatory constraints (CITES)