Like everything else, urethane elastomers age. Aging is caused by, among other things, water, heat, light, oxygen, chemicals, fatigue, microorganisms, mechanical attacks, etc. Aging types can be divided into purely mechanical aging (e.g., fatigue), thermal degradation, thermo-oxidative degradation, photo-oxidative degradation, radiolysis, acidolysis, hydrolysis, microbiological attacks, etc. Most often, it is a combination of several degradation mechanisms. One of the most common causes of severe degradation of certain polyurethanes is hydrolysis, which is caused by water and heat together (Hydrolysis is Greek and is formed from hydro = water and lysis = decomposition).