A suggestion for further experimentation. Pyrogallol in the presence of sufficient sulfite behaves in much the same manner as metol. The Nietz-Tschibissoff series places them next to each other and their redox potentials are very similar. This would indicate that metol provides an effective substitute that is far less toxic, cheaper, and more stable than pyrogallol. This pairing of phenidone and metol is what Tetenal does in Neofin Blue.