 OPUR began a study of dew condensation under laboratory conditions ; they developed a special hydrophobic film and experimented with trial installations , including a 30 square metres ( 320 sq ft ) collector in Corsica . Vital insights included the idea that the mass of the condensing surface should be as low as possible so that it cannot easily retain heat , that it should be protected from unwanted thermal radiation by a layer of insulation , and that it should be hydrophobic , so as to shed condensed moisture readily . 
