[pure-silver] Re: PMK was Re: Tri X film versions and sizes
- From: "Koch, Gerald" <gkoch02@xxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Thu, 17 Feb 2005 13:40:46 -0500
>"Activity" is too vague.
Perhaps, but we *commonly* speak of one developer being more *active*
than another not that it is *speedier* than another. I have seen the
definition stated using the word "activity".
>Is the "optimal ratio" property of the developing agent?
The ratios are very different for MQ and PQ combinations. Mason gives
weight and molar ratios for sample PQ and MQ developers. Ratio is
probably dependent on pH and other factors. There is a limited
discussion in Mason, I would love to see some more data particularly for
ascorbate developers.
>In terms of modern classification of developing agents, what are the
criteria for agents to be superadditive?
I remember glancing at a discussion of this some years ago but can't
remember where. IIRC, it depends on the electrical charges on the two
species. But it was a long time ago.
Jerry
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of Ryuji Suzuki
Sent: Thursday, February 17, 2005 1:09 PM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: PMK was Re: Tri X film versions and sizes
From: "Koch, Gerald" <gkoch02@xxxxxxxxxx>
Subject: [pure-silver] Re: PMK was Re: Tri X film versions and sizes
Date: Thu, 17 Feb 2005 12:03:51 -0500
> AKAIK, the regular definition; that the activity of the two agents=20
> combined is greater than the sum of their individual activities.
AFAIK, that's not the regular definition; the regular definition uses
the rate of development as the criteria. "Activity" is too vague.
> The optimum ratio can be determined by plotting the activity of=20
> various mixtures. Data and graphs appear in Mason where he gives=20
> weight ratios and molar ratios for Metol/hydroquinone and=20
> Phenidone/hydroquinone combinations.
And what kinds of variables can influence on the location of the maxima?
Is the "optimal ratio" property of the developing agent?
> As I stated, I have not seen any data as to the superadditivity of=20
> Metol and pyro.
In terms of modern classification of developing agents, what are the
criteria for agents to be superadditive?
--
Ryuji Suzuki
"Keep a good head and always carry a light camera."
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