Shoe insoles, also called "insoles," are predominantly made of expanded foam sheets (mostly Polyurethane – or PU for short). Unfortunately, these thermally deformed materials are only resistant to water, heat, light and sweat to a minimal extent. Due to the conditions prevailing inside the shoe (warm and humid climate and mechanical stress), increasing abrasion of the foam material is inevitable – even with occasional use. In addition, these inner sole materials age rapidly and lose their mechanical resistance after only a few weeks. So, in addition to the microplastics created by abrasion, a significant amount of waste is also generated by the necessary replacement of aging inner soles.

The biodegradable GUPPYFRIEND Insoles are made of a natural latex foam core and 100 % natural fibre felts with particularly high strength and lasting resilience. A linen-cotton textile cover is applied to the felt made of cotton, kenaf and hemp fibres using corn starch to attach the linen-cotton textile cover. Due to this air-permeable construction and the partially natural-antibacterial materials, the GUPPYFRIEND® insoles ensure a pleasantly dry shoe climate and have an odour-reducing effect.

The GUPPYFRIEND Insole can be universally adapted to the shape of your shoes thanks to its cut-to-size design. It is not only suitable for everyday shoes, barefoot shoes and any kind of sports shoes, such as hiking, football, jogging and cycling shoes.

The GUPPYFRIEND Insoles adapt to the shoe and offer light support of the foot’s arch.

Polyurethan ages. And Polyurethane, short PU, is often the material of choice for your insole. As soon as PU encounters water or moisture, a chemical process called "hydrolysis" starts. Simplified, it can be described as splitting the chemical bond by the reaction with water. The water (H2O) atoms react or break the polymer chains of the PU – from the surface inwards. Chemical additives can be used to slow down this reaction, but this causes health risks, which isn’t what we are looking for. The chemicals polyol and isocyanide used in the production of PU foam boards are incredibly hazardous to the environment and health. Transportation, processing, and disposal may result in unpredictable risks.

Last but not least, numerous, prolonged and torturous tests on mammals are necessary for the approval of the chemical’s polyol and isocyanide. We don’t want to tolerate these unmentioned side effects. And you shouldn’t either.

Your old insoles continue to lose microplastics or may end up in the environment if not dispose of properly.

Typically, they should go into the residual waste because they are reliably incinerated. But you can't say for sure: it is often not transparent what chemicals are used for the insoles and whether they would be better disposed of in the hazardous waste.