We know that the very surface of the UHMWPE ski base is created by crystalline, amorphous and transition regions. In crystalline regions no wax can penetrate, transition regions are insignificant with respect to the area, the only ski base fractions where wax can penetrate are amorphous regions.
Amorphous regions consist of disordered structure of PE molecular chains with free cavities which size is in the order of tens of nanometres. In these free cavities there is enough space for wax molecules to get in and get stuck after hot wax application.