[pure-silver] Re: PMK was Re: Tri X film versions and sizes
- From: john stockdale <j.sto@xxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Thu, 17 Feb 2005 11:44:26 +1000
At 06:52 AM 17/02/2005, Jerry wrote:
..........It is said that Metol and pyro are superadditive but I have not
seen any
>data confirming this. Even so the superadditivity ratio of Metol to
>hydroquinone is around 1:3 or 1:4 and I would suspect that it would be
>in the same range for pyro. In PMK the ratio is 1:20 which does not
>appear to be optimum. Such a high ratio is what is usually evidenced by
>Phenidone in superadditive combinations........................
Isn't the ratio of metol:pyrogallol in PMK 1:10?
John S
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