[pure-silver] Re: washing film with deminarilised water
- From: john stockdale <j.sto@xxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Wed, 02 Mar 2005 13:37:03 +1000
Thanks Ryuji.
I'll try it, and do some hypo residual tests.
Does 300ppm of sodium bicarbonate equal 300mg/Litre, or am I missing
something in the calculation?
John
=============================
At 11:04 AM 2/03/2005, you wrote:
>From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
>Subject: [pure-silver] Re: washing film with deminarilised water
>Date: Tue, 1 Mar 2005 16:28:21 -0800
>
> > As far as I can tell from the paper published by Kodak on
> > sulfite wash aid (I'll find the citation) the nature of the
> > water used after treatment is of little importance. The
> > sulfite aid also allows the use of colder water for washing.
>
>Which paper? Crabtree, King and Henn?
>
> > It also contains some EDTA tetra sodium salt and some sodium citrate
> > probably to prevent deposits of minerals from the water or to
> > prevent a sludge from forming where the wash aid is reused.
>
>That too but they also operate as antioxidants to preserve the useful
>life of the bath.
>
> > Sulfite has a specific effect as an ion exchange agent in
> > addition to its alkaline pH. It is this ion exchange
> > property which makes it far more effective than treatments
> > in alkaline salts like carbonates.
>
>You are mixing two issues here. John is talking about deliberate
>incorporation of impurities in wash water, not wash aid bath. For
>example Green (1975) found faster washing with tap water than with
>pure water. According to another publication by Green and Levenson
>(1974), they had tap water from Colne Valley at Research Division in
>Harrow. For cations, as CaCO3 equivalents, calcium was 200ppm,
>magnesium 24ppm, sodium 9.3ppm, potassium 2.8ppm. For anions, as
>sodium salt equivalents, chloride 76ppm, sulfate 56ppm, carbonate
>56ppm and nitrate 23ppm. The pH was 7.4. I would think that 300ppm of
>sodium bicarbonate added to pure water would give comparable washing
>and swelling profile to their tap water.
>
>However, I am not sure if this is advantageous after washing aid
>treatment. I am also not sure if higher dose of bicarbonate would
>further improve washing property. In another paper by Green and
>Levenson (1970) they tested dose-dependent washing profile with acid
>fixers, one hardening and one non-hardening. In that study, they used
>up to 0.16g/L of bicarbonate, wich was superior to 0.016g/L in case of
>hardening fixer. But 0.016g/L was fast enough and they didn't test
>0.16g/L for nonhardening fixer.
>
>Green, A. and Levenson, G.I.P. 1974. Emulsion swelling during
>washing, etc. J. Photogr. Sci., 22, 194-8.
>
>Green, A. 1975. Some aspects of fixation and washing.
>Photogr. Sci. Engr., 19, 124-9.
>
>--
>Ryuji Suzuki
>"Keep a good head and always carry a light camera."
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