In order to check both the change of different materials as measured by artificial degradation tests and the classification of materials based on short term exposure, a weathering program involving exposure of up to ten years' duration was set up. This program includes the study of several transparent and opaque poly(vinyl chloride), translucent glass-reinforced polyesters and opaque molding compounds, a common polycarbonate, and elastomeric materials. Each weathered polymer was characterized in terms of its aspect properties and optical properties.