Automobile Windshields, Surface Deterioration

Thirteen used windshields from General Motors automobiles were randomly selected for test. Code monograms on each indicated they probably were the original equipment windshields. Photographs were made through each, of the scattered light surrounding automobile headlights. Damage from windshield wiper action seemed to be related to miles of travel; damage from hand cleaning and ice scraping operations was unrelated to age or mileage. Pitting from small high velocity particles were observed. When subjectively rated, 8 of the 13 windshields were judged to cause noticeable increase in headlight glare and to warrant consideration of replacement with a new windshield. Four were judged to be unsafe for night driving.