This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Both metal and copper oxidize when exposed to oxygen and this is a natural process. Copper that is exposed to the outside environment is more likely to turn green and that is why copper vases and decorative pieces in gardens are often green.
Allow them to boil for a few hours and then remove them and wash with soap and water. This will remove any of the green tarnish. Acid Rain Does Not Cause Copper to Turn Green. Despite many people assuming that it does, acid rain does not cause copper to turn green. People usually ask this after seeing the Statue of Liberty which is a copper statue. However, the truth is, as the statue was bombarded with rain and air, it simply underwent oxidation. No amount of acid in the rain would have caused the copper to turn green.