[pure-silver] Re: Fishy developer: NOW Triethanolamine
- From: "Koch, Gerald" <gkoch02@xxxxxxxxxx>
- To: "'pure-silver@xxxxxxxxxxxxx'" <pure-silver@xxxxxxxxxxxxx>
- Date: Fri, 17 Dec 2004 15:44:03 -0500
I wasn't suggesting that there would be a buffer between the TEA and the glycol
but rather that by having less TEA the pH of the solution would be less.
My version of the formula is that I dissolve the Phenidone and the ascorbic acid
in 100 ml of hot propylene glycol. I allow the solution to cool and add 100 ml
of TEA. This prevents the solution from becoming so brown which I take to
indicate that there is less decomposition of either the Phenidone or the
ascorbic acid then if they had been added to hot TEA. I then use twice the
amount as would be required if there was only TEA. The solution is far less
viscous and easier to measure.
It appears that Pat Gainer has updated his formula to contain 0.2 g of potassium
bromide per 100 ml of concentrate. This small amount reduces fog experienced
with some films such as 400Tmax.
Hydroquinone is readily soluble in both TEA and propylene glycol.
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx [mailto:pure-silver-bounce@xxxxxxxxxxxxx]
On Behalf Of John Black
Sent: Friday, December 17, 2004 3:11 PM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: Fishy developer: NOW Triethanolamine
> One doesn't have to use straight TEA as the solvent in the Gainer
> formula.
The
> solvent could be and mixture of TEA and propylene glycol or something
similar.
> This would drop the pH of the concentrate and also the working
> solution.
>
> Jerry
>
Correct. Gainer showed that any of the glycols and/or TEA would work as a
solvent for the reactants. However, he did like using only TEA as solvent and pH
control for the sake of simplicity. TEA liquid is a viscous liquid and I, for
one, dislike using it because it is difficult to measue accurately. If the TEA
is diluted 1+1 (1:2) with methanol, it become fluid and is much easier to
handle.
I doubt that there would be sufficient interaction between TEA and the glycols
to form a buffer.
BTW, as an aside, my favorite developer is a PC using Tris-amino methane/boric
acid as a buffer (pH 8.3). The PC is dissolved in dry methanol (wood alcohol) as
the solution A. I dissolve 10gm ascorbic acid in 120ml methanol first and then
250mg phenidone. Ascorbic acid is soluble with gentle heat (80-100 degrees) in
methanol up to the saturation point which is between 9 and 10gm per 100ml. I
found the other night, that sodium ascorbate (the neutralized form of vitamin C
used in Xtol) is essentially insoluble in methanol at any temperature. So that
eliminates sodium ascorbate from my formulas.
Oh well... next I will see if I can put a small amount of hydroquinone in there
and boost shadow detail a bit.
JB
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