I need a strong oxidizer to break down some copper but I don't have access to anything that would be restricted to a chem lab (such as concentrated nitric acid). Are there any common chemicals I could buy from a hardware store that are very strong and fast working oxidizers? Even just a concentrated source of nitrate would be good; I have lots of hydrochloric acid I could add to it. Don't say bleach. At only 5.25% sodium hypochlorite, it's very slow and quite expensive for how much one really gets (it's mostly just water).