Michael wrote:(posted 9592 days ago)PMK was formulated by Gordon Hutchings ten or so years ago and was not available to Edward Weston or Ansel Adams.
I'm certainly no expert on photographic processes, but found the following in John S. Carroll's "Photographic Lab Handbook", fifth edition 1979, ISBN 0-8174-2486-5:
Trihydroxybenzene (pyragallol, pyrogallic acid, pyro, and so on) is an early developer, now all but obsolete. It produced a variety of results depending upon the alkalinity of the developer in which it was used; thus, it was a highly flexible developer, but its severe staining tendency caused it to lose popularity as more modern as more modern developing agents came into use.
So, I take it Hutchings' PMK formula is recent, but the use of pyro in developers is relatively ancient? It is mildly amusing to note the comment in Carroll's text that the stain is a liability.
Dana K6JQ Dana@Source.Net