"Keith Tapscott."
wrote in message
...

Most B&W developers contain Hydroquinone with either Metol
or Phenidone
or a Phenidone derivative. Both Metol and Phenidone are
super-additive
with Hydroquinone, so why add both of them in the same
developer
formula?

Here is an example of a developer which contains all three
of those
constituents.
http://www.tetenal.com/sidaopener_uk...auk/100152.pdf




--
Keith Tapscott.

Its interesting also that it contains both potassium
carbonate and sodum metaborate. There are some developers,
notably Kodak D-7, a pyro-metol developer, where the metol
serves mainly as a preservative for the pyro. Metol is a
prodigeous oxygen absorber. Its also curious that its the
only ingredient in the MSDS which has detailed hazards
although hydroquinone is usually considered more hazardous
than metol.


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--
Richard Knoppow
Los Angeles, CA, USA