Shoes made 100 years ago by local shoemakers from leather and leather soles had a major disadvantage of low durability of the leather soles, so they had to be scuffed, which means that the sole had to be attached from the bottom. However, this footwear was completely biodegradable and CO₂ neutral. But by using rubber and other synthetic materials with long life and better abrasion resistance, the footwear became a burden on the environment, since rubber, PVC, and other synthetic materials take centuries to decompose in rubbish dumps.
The development of reactive polyurethane sole compounds has changed that. Such polyurethanes are close to proteins in their composition, and are degradable, which until now seemed to be a disadvantage because the polyurethane soles started to crumble even on unworn shoes after about 8 years.
The biodegradability of the insole can be achieved by modifying the formulas of the production of the reactive polyester polyurethane insoles, removing the silicone stabilisers, and using natural dyes such as carbon black and titanium white. The non-biodegradability of synthetic materials is the biggest problem of our civilisation right after CO2 emissions.
The biodegradability of other parts of the shoe - replacement of polyester threads and laces with cotton ones, replacement of chrome-treated leathers with tanned ones - is no longer impossible, it's just more expensive.
Using all the components that make up the footwear in a biodegradable design makes the entire shoe biodegradable as well.
We are working on developing compostable footwear where the entire shoe could be put in a composter and the entire shoe would decompose into compost, CO₂, and water within a few years. We are currently working on the development and testing of such a product with the T. Bata University in Zlín.