Organic glass is not the same as the glass in windows — the organic glass contains carbon in a structure that can easily deform due to sunlight. The upper schematic shows a comparison of two sets of organic glass films prepared by two methods and then exposed to light, resulting in color changes after extended times. On the right side, the film prepared by the cooling of a liquid (called ordinary glass, OG) readily changes color when exposed to light (or photoreacts). On the left side, the film prepared by vapor deposition has a densely packed molecular structure (called stable glass, SG) that prevents the photoreaction and hence the degradation. The reason for the color change is depicted in the bottom schematic showing that the molecular structure changes in response to light.