[pure-silver] Re: Adding Sodium Sulfite to Sodium Thiosufale.
- From: Gerald Koch <gerald.koch@xxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Mon, 4 Apr 2011 10:10:43 -0700 (PDT)
May I answer for John being trained as a chemist. Sodium thiosulfate solutions
are mildly alkaline. A 5% solution has a pH of 8.0.
Jerry
________________________________
From: Bogdan <bkarasek@xxxxxxxxxxxx>
To: pure-silver@xxxxxxxxxxxxx
Cc: John Stockdale <j.sto@xxxxxxxxxxx>
Sent: Sun, April 3, 2011 6:47:16 PM
Subject: [pure-silver] Re: Adding Sodium Sulfite to Sodium Thiosufale.
Hi John, it's been a while since I did my college chemistry..... what is the pH
of Sodium Thiosulfate. Is it neutral?
And where does one get Sodium biSulphite? or is it a house hold product , like
baking soda, Sodium BiCarbonate.
Bogdan
On 4/3/2011 5:02 PM, John Stockdale wrote:
A weak solution of sodium bisulfite makes a good stop bath which I think is
more
compatible with a neutral fixer (I use Kodak Flexicolor Fixer, a rapid fixer
made for colour materials but near neutral, pH=6.5 approx).
>
>John
>
>============
>
>Bogdan wrote:
>Thank you for the input, Michael. I'll see about the Sodium BiSulfite
>although
>I have Sodium Sulfite readily available.
>>
>>Anchell's recommendation is for 480 gr of Sodium thiosulfate per 2 L of water.
>>
>>Cheers,
>>Bogdan
>>
>>On 4/3/2011 8:13 AM, Michael A. Smith and Paula Chamlee wrote:
>>Bogdan,
>>>
>>>I use an acetic acid stop bath. I then use plain sodium thiosulfate with
>>>15-25
>>>grams added of Sodium Bisulfite per 1/2 gallon or 40-50 grams of Sodium
>>>Bisulfite per gallon.
>>>
>>>Many years ago, when I spent a month with Brett Weston, watching him print
>>>most
>>>every day, this is what he used. I figured if it was good enough for Brett,
>>>who
>>>learned to do this from his father, it was good enough for me.
>>>
>>>
>>>Brett used the higher number in the quantity range above. Paula does not
>>>like
>>>the smell of the Bisulfite when she gets close to it, so she has cut down
>>>the
>>>quantity with no adverse affect.
>>>
>>>
>>>When the Bisulfite is not used, and there is only the plain sodium
>>>thiosulfate,
>>>the solution soon gets quite cloudy (though seems to continue working). When
>>>the
>>>Bisulfite is added, it clears right up.
>>>
>>>I use a two-solution fixing bath. The first bath only gets the Bisulfite.
>>>Then I
>>>use a holding bath and at the end of the day I rotate finished prints
>>>through
>>>a second fixing bath, this time with plain sodium thiosulfite only and no
>>>Sodium
>>>Bisulfite.
>>>
>>>I then take the prints directly into a Perma=Wash/Rapid Selenium Toner
>>>Solution.
>>>I have never had any staining.
>>>
>>>
>>>Using 480 grams of Sodium Sulfite per two liters of hypo seems to me to be
>>>beyond excessive. That is a lot of Sodium Sulfite. Mt recommendation is to
>>>ignore Anchell's recommendation.
>>>
>>>Michael A. Smith
>>>
>>>
>>>
>>>On 4/2/11 5:48 PM, Bogdan wrote:
>>>hi all,
>>>>
>>>>In the discussion on using 2 bath Sodium thiosulfate, someone mentioned
>>>>adding
>>>>Sodium sulfite to prolong the keeping properties of simple hypo.
>>>>
>>>>I'm using Anchell's "Darkroom Cookbook" as my reference for my chemistry.
>>>>
>>>>For plain hypo, He recommends 480.0 grams of Sodium Thiosulfate per 2 L of
>>>>water; how much Sodium sulphite should I add to assure longevity.
>>>>
>>>>Till now, I have never added Sodium Sulfite to the hypo and would tone the
>>>>prints in 1:9 KRST (no additives) and then wash.
>>>>
>>>>Any suggestions of the amount I should add to the hypo?
>>>>
>>>>Cheers,
>>>>bogdan
>>>>
>>
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