Chromic acid is a solution containing compounds such as sodium hydroxide, and a variety of toxic heavy metals. It is often used as a cleaning solution for glass, especially glass equipment used in laboratories containing organic residue which cannot otherwise easily be removed. It is considered a strong acid and has several features in common with sulfuric acid and although it is not flammable, it is potentially explosive and considered hazardous because of its powerful oxidative properties.
Chromic acid is also widely used in the production of ceramic glaze, wood preservatives, colored glass, and in metal finishing. Because it is a powerful oxidizing agent, it is also often used in several common organic chemistry reagents. At one time, chromic acid was used to give metal musical instruments their distinctive yellow patina, although the practice was discontinued for health reasons. Chromic acid was also used in certain brands of hair dye during the 1940s.