Washing & Toning.

[Ryuji]

The bath I call 'conditioning bath' (= pH +/- 9), in lack of a better name, is to bring the pH level of the emulsion (after fixing = +/- pH 7) towards the one of the Selenium (= pH +/- 9.2). By this the Selenium lasts for a very long time, as a matter of fact it lasts for over an year, low pH is bad for Selenium.

As I said before, the emphasis on pH is probably misleading. As long as the print is well rinsed with plain water, selenium bath contains enough base to make the print alkaline rapidly.

Also, the working capacity of selenium toner is limited by the amount of selenosulfate ion available for toning. At typical dilution of KRST, there is less than 1g/L of selenium and this is taken up by each print toned in the bath.

This is why I use Potassiun Disulphite for the stopbath, fresh it has a pH 3.5 and after a few prints it rises verry fast up to pH 6 where it stays for a long time, and topped off every time whit fresh one, it lasts for allmoste a year.

This is not a very good idea. There is no reason to use something that costs more, smells due to sulfur dioxide gas, and doesn't do anything better than other choices. Metabisulfite doesn't really have a good buffering power at pH 6 either.

I got some ideas from the web site of Lloyd Erlick (interesting!) who allso states that dumping (wasting) chemicals not only is expensive but also very bad for the environment, he's right don' t you think so?

That's misleadingly oversimplified. If unnecessary chemical is dumped, there is no question that no dumping is better. But we need to use some chemicals to achieve good photographic goal, while using fair effort to minimize potential hazard to the darkroom workers, the sewer system, environment, etc., and also to minimize wasted chemicals, water, and also costs of ingredients, disposal, transportation, etc. Selection of formula and ingredients are a trade-off among all these and other technical factors.

The 'resting in fresh water' has been suggested by a photographer working for the archive of the Gent University. He says that by doing so there is still some fixer left over in the emulsion, not to much but just enough, what is necessary as suggested by the I.P.I. of Rochester (U.S.A.).
Because an 100 % wash, after 30 min. and HCA, is not possible, there is still a bit of fixer agent in the emulsion, the 'resting' is dilluting the rest, what's left is just 'good'.

There is no use in overwashing prints. It not only give no advantage to the print's longevity, it wastes a lot of water.

 

[Philippe-Georges]

Dear Ryuji,

First, I would like to apologise for the misspelling of your name, I hope you will not take it as a lack of respect to your person!
Also, thank you for reacting om my message.

It is always interesting to reed the suggestions by a far better instructed person.
I used to be advised by Dr. Holz at Agfa (Leverkusen), you know what append last year...

- The use of that sop bath is a habit left over of the old AGFA pro colour developing processor I used to work with, as is the FX-U (which I used to buy in 60 lit. barrels, I still have one left) in the separated bleach and fixing baths.

- I was told that acid, when it get in to the paper fibre, is rather hard to be washed out, this is why I feared low pH...

- I will try omitting the 2% Borax bath and see what happens. Then eventually, as you suggested, I can always use the 2% sodium sulphite bath, which is indeed cheaper.

- About the final wash, 20 min., who am I to doubt, and indeed Kodak advises the same when using HCA...

Thank you again.

Sincerely,
Philippe

 

[jstraw]

Reviving this thread as I'm trying to refine my work flow.

First a couple of 2-bath fixing questions. I'm using TF-4 (alkaline) 1:4 in two, sequential, two-minute steps. Now the bottle says I should get so many prints per gallon of working solution. ..but that assumes a single bath. Should I be testing for exhaustion for the first bath and at that point, make the old second bath the first bath and pour a new second bath, repeating that cycle?

What's the recomended testing solution for working strength fixer? I'm told the Edwal drops are not a reliable test.

After fixing I'm thinking that the following procedure is workable:

5 minutes in a running, holding bath
Selenium toning for tone and permanance (unsure of time and dilution *)
Holding tray
5 minutes in running, holding bath
10 minutes HCA
30-60 minute archival wash

* I've been doing 1:12 for four minutes but I don't know if that's adequate.

An HCA question... Since it's a powder, I presume that I must mix it all and that measuring out so much powder for so much working HCA is a bad idea. Is this correct?

Thanks.