Development of the PU sole

Coupled with this self-confidence is the ability to pursue successfully what may be initially little more than a hunch. This was the case with the PU sole. The material was to be a PU foam however, to be successful it would require to be flexible, and to have a closed-cell foam structure (so as not to absorb water), and a closed-cell flexible foam was considered to be impossible around 1960. However, the list of advantages ascribed to 

2 Comparison of polyurethane with other soling materials 

The advantages offered by a foamed PU sole may be listed under two headings as shown in Table 13.2. 

Low density Good traction Good thermal insulation Resilience - low fatigue Good abrasion resistance Good oil resistance 

Direct moulding to uppers Cold reaction in mould Low pressure moulding 

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