Indicator stop bath failure

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Sometime ago, I regaled this forum of a problem in my darkroom to wit; hypo that turned blue and lost it's potency. Nobody had a real good answer. Well, I got one now and it does not lead to a tranquil mind. The protocol; Printing trip snapshots from Ireland(not LF, sorry about that) onto 8x10 single weight paper, two negs on some, one on others, mounted back to back, wide borders allowing india ink annotation, to be passed around to the awed multitudes (my relatives of which there are a large number) while we talk about our trip. We are not talking archival here.

Developer: 36 oz Dektol: 1+2 water Stop: 32 oz Kodak Indicator Fix: Pure hypo Normally, I use Kodak Fixer for this, but had none mixed, hypo was.

I was printing along when I noticed that my stop, saved from a previous short session, was getting darker, no blue, a deeper yellow. I always change at that point, so I did. I was then astounded to see the hypo turn blue. Hmmm! I threw everything out and left quietly, not looking back.

In the middle of the night, Fred Picker's voice came out and said: "Test!"

After completing the run of prints the next day;

The stop had 5 single weight sheets through it. It took about 4.5 oz more developer to get it to the color at which I normally change.

The hypo had 5 single weight sheets through it. It took less than 0.2 oz of developer to develop a blue tint.

Hmmm!

Conclusion: The indicator is worthless in the stop. I had always suspected this so I never ran it to purple. Now I find it is REALLY worthless. (Unfortunately, I forgot to continue on with the developer/stop test to see what it took to turn it blue.)

Hypo apparently has no buffering against alkaline developer that gets through the stop. I would expect that Kodak Fixer would. That is probably why I have had no visible problems in "production" printing because I usually use Kodak Fixer.

I usually reserve hypo for prints that are going to be toned, spotted and (I hope ) sold. If I am using a 'known' neg, I rarely print more than five 11x14's total including trials, in one session and I use all fresh chemicals so I hope there are no photos out there fading away.

Vestal says 20 prints/qt is stop capacity. The Kodak Darkroom Guide says substantially the same thing.

RJ Harris determined that a double weight print drained at least 15 seconds until the drops are 1 sec apart, carries 0.2oz of developer into the stop. As I didn't wait that long, I guess my single weights were carrying about the same amount. I was probably around 20-25 photos when I spotted the problem, so it occured before that. I think the 20 print/qt is optimistic. Better back off to 15 WELL-DRAINED 8x10 prints.

For 'fine' printing, I usually replace my developer and hypo at 10 8x10's so the stop now goes with the other two. I refixed the photos of the day before

I thought I'd tell you folks in case you had thought that you had finally found inner peace in your dark room.

(This was also posted on LARGE FORMAT PHOTOGRAPHY)

-- Richard C. Trochlil (trochlilbb@neumedia.net), November 21, 2001

Answers

Hi, Richard. A question and a couple of opinions: how did you come to the conclusion that plain "hypo" (I take this to mean sodium thiosulfate, only, dissolved in water) is ok to use as fixer; is there literature recommending this? To the best of my knowledge, one should always have at least a slight surplus of sulfite ion in the solution; this acts somewhat like a preservative (although not in the same way it would for a developer). I have had substantial experience in desilvering and regeneration of fixers (although mostly ammonium thisoulfate based).

I really believe that your conclusion, "The indicator is worthless in the stop.", is wrong. I don't know what the actual pH indicator is, but I'm pretty sure it's going to change color at the right pH. I don't have any explanation of why the plain "hypo" solution would change color BEFORE the stop bath does although I don't believe it should when simpling cycling paper through.

If your last test consisted of simply adding small quantities of developer to the stop and fixer to look for a color change (when fixer is known to have some "indicator" in it), I would expect a plain "hypo" solution to be easily changed. The plain "hypo" (sodium thiosulfate) solution should have close to a neutral pH (about 6.5 to 7.5 or so) and no pH buffering so to speak.

My best recommendation would be not to use a plain sodium thiosulfate solution. Instead, how about Kodak's F-24? It's essentially the same thing with surplus sulfite ion and a sulfite/bisulfite pH buffering system. Here's a formula for F-24:

Water, about 125 deg F = 500ml Sodium thiosulfate (pentahydrate) = 240 grams Sodium sulfite, desiccated = 10 grams Sodium bisulfite = 25 grams Top off with cold water to about 1 liter

(Formula from IS&T's "Handbook of Photographic Science and Engineering")

-- Bill C (bcarriel@cpicorp.com), November 21, 2001.


Whoops! Lost the formatting on that formula.

The formula is listed with "component", then " = ", then "amount". It should have started new lines after the weight.

-- Bill C (bcarriel@cpicorp.com), November 21, 2001.


The stop was from some work earlier in the day. Should have thrown it out.

Lootens, and Picker recommend pure hypo if you are going to tone. Vestal kind of hints at it, in one of his articles he noted that he buys hypo in bulk. In fact, Picker and his successor at Calumet sell the stuff.

I think my water supply has something to do with it. When I lived in a previous life in another place, I could use Kodak Fixer and still spot and tone. Difficult to do that here for some reason and I think it is the water. Of course, maybe they changed the Kodak Fixer or the papers. One never knows.

Adams talks about the 'slimy' feel, but I never could get it.

Anyway, for you two people out there using pure hypo, I thought you would find this interesting. BTW, Lootens makes it very clear that pure hypo is very fragile. I should have paid closer attention.

-- Richard C. Trochlil (trochlilbb@neumedia.net), November 21, 2001.


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