[pure-silver] Re: Adding Pot Bromife to PC-TEA
- From: Sandy King <sanking@xxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Mon, 3 Jan 2005 18:05:56 -0500
I experimented with Pat Gainer's PC-TEA solution in the spring and
found that it produced too much fog for my taste. After some testing
I found that about 0.2 g of potassium bromide per 100ml of PC-TEA
brought the B+F of Ilford FP4+ down to about log 0.08 without any
loss of emulsion speed. That is a fairly well formulated solution in
my estimation. I also tested benzotriazole with the PC-TEA formula
and found that about 1ml of a 1% solution of benzotriazole mixed in
glycol could be added to the PC-TEA stock solution, with about the
same results in terms of reduction in B+F.
One could also take other steps to lower the alkalinity of the
working solution, but that would be a lot more complicated than
simply adding bromide or benzotriazole, and to what purpose? Would
this give negatives of finer grain, more effective emulsion speed or
more acutance?
Sandy
>I am having a bit of fun experimenting at the present time. I'm not shooting
>very much film at present and find myself discarding film developer that has
>become too old. I was attracted to the idea of a waterless concentrate
>developer like HC-110 with a long shelf life. Such a developer was
>suggested by
>Pat Gainer in PhotoTechniques.
>
>I didn't like the negatives produced by his formula. There was a
>recent post on
>APUG where he suggested adding a small amount of potassium bromide.
>Kodak uses
>an addition product of hydrogen bromide and diethanolamine as a source of
>bromide ion in HC-110. KBr is slightly soluble in TEA, obviating the need to
>find a source of diethanolamine hydrobromide. The ammonium salt seems to be
>more soluble in organic solvents. I considered benzotriazole since it is very
>soluble in various glycols, but wanted to try bromide first.
>
>A concentrate containing 9 g of ascorbic acid, 0.3 g Dimezone-S and
>0.2 g KBr in
>100 ml of propylene glycol+TEA diluted 1+49 produces some very nice looking
>negatives. Hope to do some printing tonight.
>
>-----Original Message-----
>From: pure-silver-bounce@xxxxxxxxxxxxx
>[mailto:pure-silver-bounce@xxxxxxxxxxxxx]
>On Behalf Of Ryuji Suzuki
>Sent: Monday, January 03, 2005 4:10 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: Mon, 3 Jan 2005 15:59:04 -0500
>
>> BTW, data on ammonium bromide seems to indicate that it would be
>> easier to dissolve than the potassium salt. I have not tried this out
>> as yet.
>
>Ideally, I would start with a carefully formulated developer to
>avoid all these
>issues. What is the aim of dealing with a developer with troubles like this?
>
>I'd not even consider ammonium salt in a fine grain developer. Tertiary amines
>like triethanolamine is a way to control the solvent effect of
>ammonium ion. If
>KBr doesn't work, I would look into 6-nitrobenzimidazole or
>1-phenyl-5-mercaptotetrazole. The latter is used in quantity like 2-20mg per
>liter of working solution anyway.
>--
>Ryuji Suzuki
>"Keep a good head and always carry a light camera."
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