The polyurethane is a polymerizing material containing groups of type - NH-CQ-Q- and obtained with the reaction of a poliolio with an isocyanetic one. The possibility to vary relationships and types of raw materials concurs to obtain an immensest variety of products and with such characteristics from being able to cover an immense range of applications. The polyurethane offers the advantage of a plastic material that can be easy modeled and that it groups arranged salienti characteristics together. It can be rigid, resistant to the abrasion like a ceramic or extensible product like the rubber. It will not be sure possible that the polyurethane resolves all the technical problems but really we are convinced that to such aim can give a serious contribution. According to the fields of employment, and the mechanical sollicitations or chemistries to which they are subordinates, the products and the coverings in polyurethane they can assume characteristics of: