Ageing and wear: How materials change over time

Shoes accompany us every day – in sunshine, rain, cold or heat. But even if they appear to be indestructible, numerous factors affect their materials and construction over time. To enable manufacturers to understand how their products change under long-term conditions, tests are carried out in laboratories to simulate the ageing and wear of materials.

What happens during ageing/wear and tear?

The tests simulate the stresses to which materials are exposed throughout their service life – but in a much shorter period of time. The aim is to test long-term durability under controlled, defined conditions. Various influences are specifically simulated in the process:

• Exposure to light: Over time, sunlight causes fading, embrittlement and loss of strength. In the laboratory, special exposure chambers simulate this effect in just a few days.
• Heat and time: Increased temperatures accelerate chemical ageing processes – ideal for making material changes visible at an early stage.
• Moisture: Particularly important in footwear, as inner linings, adhesives and upper materials regularly come into contact with moisture.
• Mechanical stress: Repeated rubbing, bending and folding, for example, realistically simulate use over a long period of time.

Why is ageing and wear behaviour so important?

While climatic storage simulates short-term stresses such as extreme heat/dryness, heat & humidity or cold, tests relating to ageing and wear and tear show how materials change over time.
This allows weak points to be identified before they occur in real-world use – such as:

• Loss of elasticity in sole materials
• Colour changes or yellowing
• Embrittlement of synthetic materials
• Delamination of adhesives
• Impairment of coatings, finishes or membranes
• Severe material abrasion

The result: reliable statements about the service life and quality of a product.

An important component for durable and sustainable products

Specific tests play a crucial role in developing more sustainable products. Understanding how materials age and wear allows designers to focus on durable constructions and suitable material combinations.
This not only extends product life, but also reduces resource consumption and waste – a direct contribution to greater sustainability in the footwear industry.

An important component for durable and sustainable products

Tests conducted under defined conditions can determine what happens when time, climate, light exposure and use leave their mark. These processes can be simulated in a controlled manner in the physics laboratory, allowing materials to be analysed – an important basis for developing products that will continue to function reliably even after many years.