FAQs: Material Guide: What Is Rubber? And Is It Sustainable?

Rubber is a versatile material used in various products, including footwear. However, questions about its production, usage, and sustainability often arise. This FAQ guide aims to provide a comprehensive understanding of rubber, its applications in shoes, and its ethical and environmental implications.

What is Rubber?

Rubber is a natural or synthetic material known for its elasticity, durability, and waterproof properties. There are two primary types of rubber:

  • Natural Rubber: Derived from the latex sap of rubber trees (Hevea brasiliensis). This type of rubber is harvested by tapping the trees to collect the sap, which is then processed into usable rubber.
  • Synthetic Rubber: Produced from petrochemical sources, synthetic rubber mimics many properties of natural rubber. It's made through a chemical process involving the polymerization of monomers like styrene and butadiene.

How is Rubber Made?

Natural Rubber Production:

  1. Harvesting Latex: Rubber trees are tapped, and latex sap is collected in cups attached to the tree.
  2. Coagulation: The latex is treated with acids to solidify the rubber particles.
  3. Processing: The solid rubber is then rolled into sheets or blocks and dried for further use.

Synthetic Rubber Production:

  1. Polymerization: Monomers such as styrene and butadiene are chemically bonded to form long polymer chains.
  2. Mixing: Various additives are mixed with the polymers to achieve desired properties like strength and flexibility.
  3. Shaping and Curing: The rubber is shaped into the desired form and then cured through heating, which helps set the material.

How is Rubber Used in Shoes?

Rubber plays a crucial role in the footwear industry due to its unique properties. Here's how rubber is commonly used in shoes:

  • Outsoles: Rubber provides excellent traction and durability, making it ideal for shoe outsoles. It helps prevent slipping and withstands wear and tear.
  • Midsole Cushioning: Rubber can be used in midsoles for cushioning and shock absorption, enhancing comfort during walking or running.
  • Waterproofing: Rubber is naturally waterproof, making it suitable for rain boots and other waterproof footwear.
  • Flexibility: Its elasticity allows for flexible shoe designs that adapt to the foot's movement, providing comfort and support.

Is Rubber Ethical and Sustainable?

The sustainability and ethical implications of rubber production vary depending on the type and method of production:

Natural Rubber:

  • Environmental Impact: Harvesting natural rubber can be sustainable if done responsibly. Rubber trees can be tapped for many years, and rubber plantations can help sequester carbon.
  • Deforestation: However, large-scale rubber plantations can lead to deforestation, loss of biodiversity, and habitat destruction if not managed properly.
  • Fair Trade: Ethical concerns include ensuring fair wages and working conditions for workers on rubber plantations. Certifications like Fair Rubber can help ensure ethical practices.

Synthetic Rubber:

  • Environmental Impact: Synthetic rubber production relies on non-renewable petrochemicals, contributing to pollution and greenhouse gas emissions.
  • Waste: Synthetic rubber is not biodegradable, leading to waste management challenges. Recycling programs can help mitigate this issue but are not universally available.

Innovations and Alternatives:

  • Recycled Rubber: Using recycled rubber in shoes can reduce waste and reliance on virgin materials.
  • Bio-based Synthetic Rubber: Researchers are developing bio-based alternatives to traditional synthetic rubber, aiming to reduce the environmental footprint.


Rubber is an essential material in the footwear industry, offering durability, flexibility, and waterproof properties. While natural rubber can be sustainable if harvested responsibly, synthetic rubber poses environmental challenges due to its reliance on petrochemicals. The key to ethical and sustainable rubber use lies in responsible sourcing, fair labor practices, and advancements in recycling and bio-based alternatives. By understanding these factors, consumers and manufacturers can make more informed choices towards sustainability.