what chemicals can color metal
You can color any metal containing iron, such as steel, with the oven heat of an ordinary kitchen range. Depending on the temperature setting, the steel changes color across a spectrum of shades ranging from pale yellow to dark blue. In addition, literally hundreds of chemicals will change the color of metal surfaces. Some of them are too toxic for amateurs to use. For example, cyanides, nitric acid, chromic acid, mercuric chloride, and lead acetate are hazardous chemicals only professionals should attempt to use.