Industry uses selenium to manufacture photocells, photographic exposure meters, solar cells, and rectifiers for home entertainment equipment. Further uses are in metal alloys, xerography, red or black glass, anti-dandruff shampoos, pigments in plastics, paints, dyes, enamels, inks, textiles, rubber (accelerator and vulcanising agent), photographic emulsions, and petroleum. It is also used in veterinary medicine, in medical therapeutic agents, as a nutritional feed additive for poultry and livestock, and as a fungicide and insecticide. Uses in electronics and photography account for the majority of selenium use, followed by the glass industry, then pigments. Some applications for specific selenium compounds follow. Selenium dioxide is the most widely used selenium compound in industry. It is used as an oxidising agent in drug and other chemical manufacture, a catalyst in organic syntheses, and an anti-oxidant in lubricating oils. Selenium sulfide is used in anti-dandruff shampoo. Selenous acid can be found in gun blueing solution which is used to clean the metal parts of a gun.