[pure-silver] Re: Adding Pot Bromife to PC-TEA
- From: "John Black" <jblack@xxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Mon, 10 Jan 2005 17:33:29 -0500
> What the article said was that even after adjusting for the difference in
> molecular weight, replacing Phenidone with a substituted Phenidone
resulted in
> somewhat less activity. I read this on the internet but couldn't find a
> reference in my notes. I may not have kept a copy since the article did
not
> give specific values.
>
This is exactly what I have found to be true using Dimezone, Dimezone-S and
Phenidone side by side in tests for activity. It's not a profound
difference, but noticable. When concentrations are adjusted for molarity,
on a scale of 100, I find phenidone to be a 100, Dimezone-S to be an 80 and
Dimezone to be about a 65.
Hard to beat phenidone if you can stabilize it.
JB
> Jerry
>
> -----Original Message-----
> From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx]
> On Behalf Of Ryuji Suzuki
> Sent: Friday, January 07, 2005 6:13 PM
> To: pure-silver@xxxxxxxxxxxxx
> Subject: [pure-silver] Re: Adding Pot Bromife to PC-TEA
>
>
> From: "Koch, Gerald" <gkoch02@xxxxxxxxxx>
> Subject: [pure-silver] Re: Adding Pot Bromife to PC-TEA
> Date: Fri, 7 Jan 2005 17:35:10 -0500
>
> > I have always thought that Gainer's formulas tend to use too much
> > Phenidone. His initial P/A ratio was 1:36 (0.25:9). If you make the
> > necessary conversions in the Xtol formula you get a ratio of 1:69.
> > Some other commercial film developers are even smaller 1:80 or 1:90.
> > I was wondering if this was the cause of the fog and poor tonal
> > separation that I was seeing.
>
> Optimal range of phenidone-to-ascorbate ratio varies depending on the pH,
> absolute concentration and other factors like antifoggant. I think his
> developers are very often off balance because he has some unusual goals
like
> removing sulfite, removing water, or manybe some other photographically
> irrelevant goals. At one time he was trying to prove sulfite doesn't do
anything
> in developer, and he even sent me negatives of his test runs. I could
easily
> see the effect of sulfite at 5x magnification, and even more clearly at
12x, but
> he didn't see it at all. I didn't know what to say. I sent him a stack of
xerox
> of some background info on chemistry of developers, but I don't know what
> happened after that.
>
> The fog level is mostly determined by the phenidone level, pH, and
antifoggant.
> Ascorbate is out of the equation besides its influence on pH and perhaps
ionic
> strength when it comes to fog. Ascorbate is pretty much incapable of
developing
> AgX crystals by itself in presence of gelatin.
>
> > However, the substituted phenidones are said to be less efficient
> > compared to phenidone even when the difference in molecular weight is
> > taken into consideration.
>
> Who said that in what context? Do you have a ref for that? I do know
methyl and
> dimethyl substitution at 4 position make some difference, but I would like
to
> know what is your source for this.
>
> --
> Ryuji Suzuki
> "Keep a good head and always carry a light camera."
>
============================================================================
====
> =============================
> To unsubscribe from this list, go to www.freelists.org and logon to your
account
> (the same e-mail address and password you set-up when you subscribed,) and
> unsubscribe from there.
>
============================================================================
=================================
> To unsubscribe from this list, go to www.freelists.org and logon to your
account (the same e-mail address and password you set-up when you
subscribed,) and unsubscribe from there.
>
=============================================================================================================
To unsubscribe from this list, go to www.freelists.org and logon to your
account (the same e-mail address and password you set-up when you subscribed,)
and unsubscribe from there.
Other related posts:
