My acid has turned brown. Is it still good?
If your acid is brown, first determine if the bottle or the acid has discolored by pouring a small amount into a beaker. The common culprit for discolored acid is a small amount of organic material such as paper or oil dissolved in the acid. The acid is still useable as an acid and frequently solutions made from discolored acid are colorless. A slightly discolored bottle may be due to the discoloring of the PVC coating which does not affect its performance.