This formula uses sulfuric acid. It is dangerous stuff. Always wear goggles.
Intense heat is generated when it's mixed with water to dilute it.
Always add acid to water, never pour water into concentrated acid. Toxic hydrogen sulfide gas can be released when it reacts with organic material. Never use a metal container. For making the dilution Pyrex is best - regular glass could shatter, splattering hot acid everywhere, if it heats up too much. An acid bath in which an electrical current is passed through the part.