As power lines are built in contaminated environments, the industrial usage of power-line materials requires high reliability. Nonceramic insulators offer better anticontamination performance than that of the traditional ceramic insulators. Among the nonceramic materials, EPDM and silicone rubber provide much better long-term pollution resistance performance than that of any other materials. This study investigated the long-term pollution performance by a corona aging treatment on the surface of the test slabs, which were made of EPDM and silicone rubber. Experimental results showed good hydrophobicity of those materials and their transfer of the contaminant layer deposited on the shed surface of the insulator. The EPDM and silicone rubbers are synthetic polymers of low density and they maintain an outstanding resistance to attack by oxygen and ozone. This study measured the contact angle between water droplets and other materials to determine the hydrophobicity and recovery ability of these synthetic polymers. We also studied surface morphology for a visual confirmation of the migration phenomena.