The chemical Pyrogallol is an active agent in Pyro film developers.

At one time, Pyro was a universally used developer. It was even available in prepackaged formulas from companies such as Eastman Kodak. Unfortunately, it has been almost entirely replaced by metol-hydroquinone and Phenidone-hydroquinone type developers.

The main reasons for that are the fact that Pyro stains, it must be handled carefully, and it does not keep well in solution.