What ingredient in rust remover is bad?
As you can imagine, the answer to that is totally dependent on what brand of rust remover you are using and it’s method of action. Many simply burn off the rust by reacting it with hydroxide and leaving a metallic iron behind (such as the link below). This is then suitable for painting, etching, etc. In that case, the hydroxide element is what is bad. Other rust removers (which aim to change the rust back to iron), contain reductive compounds that are chemically reactive. These are very harmful compounds.
