Re: physical developers

> While this solution is fully capable of chemical development (if it
> makes imagewise development... not just fog...) how can you argue that
> this is a physical developer? Well, I can see one way that is
> possible, but still the mechanism is very different from Lumiere and
> Seyewetz's developer or other classic ones. This SP-4 seems like a
> developer that develops developable grains by means of chemical
> development, and then grow the developed grains at the cost of
> undeveloped grains, but I wouldn't put it in the same class as others.

You are right. SP-4 differs from a "traditional" physical developer. Like I
did in a previous post I should have called that type of developer
"colloidal (or solution-physical)developer". Whereas in physical development
silver is supplied externally, colloidal developers contain strong silver
solvents to provide the silver from the emulsion's own silver halide grains.
The result of the developing process might be the same in both cases
(Lumière/Seyewetz' physical developer or SP-4): formation of colloidal
silver.

Martin

----- Original Message -----
From: "Ryuji Suzuki" <rs@silvergrain.org>
To: <alt-photo-process-l@sask.usask.ca>; <martinm@SoftHome.net>
Sent: Wednesday, August 25, 2004 9:27 AM
Subject: Re: physical developers

> From: MARTINM <martinm@SoftHome.net>
> Subject: Re: physical developers
> Date: Wed, 25 Aug 2004 08:34:59 +0200
>
> > Yes, there was a Russian developer, introduced by Valery Petrov:
> >
> > SP-4
> > sodium sulfite.................85 g
> > hydroquinone.................8,9 g
> > potassium hydroxide.....7,2 g
> > phenidone......................0,3 g
> > ammonium thiocyanate..22 g
> > water...................................1L
> >
> > Development time is 5 - 10 seconds!
>
> While this solution is fully capable of chemical development (if it
> makes imagewise development... not just fog...) how can you argue that
> this is a physical developer? Well, I can see one way that is
> possible, but still the mechanism is very different from Lumiere and
> Seyewetz's developer or other classic ones. This SP-4 seems like a
> developer that develops developable grains by means of chemical
> development, and then grow the developed grains at the cost of
> undeveloped grains, but I wouldn't put it in the same class as others.
>
> --
> Ryuji Suzuki
> "You have to realize that junk is not the problem in and of itself.
> Junk is the symptom, not the problem."
> (Bob Dylan 1971; source: No Direction Home by Robert Shelton)
Received on Wed Aug 25 05:41:27 2004