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 sing le weight paper, two negs on some, one on others, mounted back to back, wide bor ders 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. W e 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 se ssion, was getting darker, no blue, a deeper yellow. I always change at that po int, 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 devel oper 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 dev eloper to develop a blue tint.
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. (Unfortunatel y, I forgot to continue on with the developer/stop test to see what it took to t urn it blue.)
Hypo apparently has no buffering against alkaline developer that gets through th e 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 hop e ) sold. If I am using a 'known' neg, I rarely print more than five 11x14's to tal including trials, in one session and I use all fresh chemicals so I hope the re are no photos out there fading away.
Vestal says 20 prints/qt is stop capacity. The Kodak Darkroom Guide says substa ntially the same thing.
RJ Harris determined that a double weight print drained at least 15 seconds unti l the drops are 1 sec apart, carries 0.2oz of developer into the stop. As I did n't wait that long, I guess my single weights were carrying about the same amoun t. 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 WEL L-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.