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#1
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Metol, Phenidone & Hydroquinone.
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 |
#2
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Metol, Phenidone & Hydroquinone.
"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. I've wondered the same thing. There are a number of developer formulas that have more than two developing agents in them, sometimes puzzeling combinations. My chemistry is not good enough to know why. -- -- Richard Knoppow Los Angeles, CA, USA |
#3
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Metol, Phenidone & Hydroquinone.
"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. -- -- Richard Knoppow Los Angeles, CA, USA |
#4
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Quote:
It may or may not contain a restrainer or perhaps it contains more than one restrainer. |
#5
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Metol, Phenidone & Hydroquinone.
"Keith Tapscott." wrote in message ... Richard Knoppow;848656 Wrote: 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. Richard Knoppow Los Angeles, CA, USAWhat I also found interesting was that there was no mention of the preservative(s) or of any restrainer(s). It makes you wonder if sulphite alone is the preservative, or whether it contains sulphite and bisulphite or metabisulphite. It may or may not contain a restrainer or perhaps it contains more than one restrainer. -- Keith Tapscott. Well, keep in mind that MSDS are legal not scientific documents and are often written as much to obscure the formula as anything else. MSDS do not have to list materials which are considered harmless or which are present in small amounts. Also, I think this is a copy of a German MSDS where the rules may be different than in the US. An example is T-Max developer. AFAIK these contain a form of Phenidone but its not mentioned in the MSDS, at least the older ones. There are other substances that fill the function of sulfite, they are found in liquid concentrates, see the MSDS for developers like HC-110 for example. Sometimes better information can be found in patents but they can also be written to obscure information. -- Richard Knoppow Los Angeles, CA, USA |
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