Wow. That's interesting, and very odd. But it sure does explain a lot of things. I would think both D76 and Xtol would be buffered to withstand fluctuations in water quality, but that's a big difference you're showing.
One more piece of information: the pH of the Kroger distilled water measured between 5.2 - 5.5 pH. Tap water measured between 7.5 -7.8 and the bottled drinking water I used to mix the 76 came in just a smidge above 7.8.
Distilled water isn't even close to the 6.5 - 7.0 I expected!
I also found a thread from '09 where PE also indicated that distilled water is acidic. Since 76 is only around pH 8.5, mixing with distill water would certainly seem to be capable of degrading 76, especially when diluting 1:1 with distilled.
This might also explain what was constantly killing my Xtol in just a week or two, in addition to the DO.
Wow. That's interesting, and very odd. But it sure does explain a lot of things. I would think both D76 and Xtol would be buffered to withstand fluctuations in water quality, but that's a big difference you're showing.
I would have thought the pH of any water can drop as it absorbs gases such as CO2. Perhaps distilled/deionized water can drop slightly more. But since water has virtually no buffering strength I'd have still expected this to have an insignificant effect on even weakly buffered developers. And XTOL is fairly well buffered.
extremely frustrated with D76 that progressively weakens from day one and Xtol that would go off anywhere from a week to three weeks. Been using the same brand of distilled water from my local market for over 10 years now and the last batch of 76 was mixed with bottled water and has been holding well; no evidence of weakening so far (getting close to 10 rolls). No problems with any liquid developers, just the ones in powder form including mixing from scratch.
Please feel free to offer an opinion if you have any thoughts on the problem.
Fred,I too am a non chemist but it may be the case that liquid developers hold up because the only water used is that for the dilution and then is used instantly whereas the powder stuff sits in the suspect water for a long time while being slowly used up. Mind you if the water from your local market is the same as that used for powder and has been holding well this kind of destroys what I have just said:confused:
pentaxuser
One more piece of information: the pH of the Kroger distilled water measured between 5.2 - 5.5 pH. Tap water measured between 7.5 -7.8 and the bottled drinking water I used to mix the 76 came in just a smidge above 7.8.
Do the Kodak packs mandate distilled?
To restate the issues so those who missed the finer details of the problem:
1) This problem of D76 leaders being weak (looking more like coffee stains than being opaque)
I still find this very strange. The water would have to be seriously bad. The Fenton reaction is what can theoretically bust XTOL by destroying the ascorbate. But as has been noted already packaged XTOL contains sequestering agents for this and other purposes. And even still, that wouldn't explain low D-76 activity since it doesn't contain ascorbate. For these particular packaged products to have lower than normal activity upon mixing (assuming the dry materials were fine), you'd need some kind of oxidizing compound in the water, and in material quantities. Or something which would lower or neutralize the alkalinity of the developer to a significant degree - some sort of significant acidic compound perhaps. But even then, XTOL in particular is buffered. D-76 to a lesser degree but still. Unless the water contained some compound which destroyed borates or sulfite by some other mechanism/reaction (since those are the only things XTOL and D-76 have in common).
I don't know, maybe Gerald will have some ideas, but this would have to be some very bad water. I'm still not buying this. There has to be another explanation. All things considered these developers (the packaged commercial versions) are quite robust.
Now I kind of wish I still had some 35mm Tri-X. I'd be happy to send you all and any leaders from processing that film, but I stopped using it in favor of HP5+. If you can use any of those leaders with D76 I'd happily send them to you.
I'm starting to think that the Kroger demineralized water needs to be analyzed.
Gerald, are there no other known ways to kill developer activity with Xtol other than iron and copper ions? No pollutants, or something perhaps from the bottles?
Thomas, a quick check is can you hold your developed leader up to your eye while outside and see through it? Most of my leaders dev'd in liquid I cannot see but the faintest detail through the leader; the leaders dev'd in 76 with this new batch are just very slightly more translucent than the liquid dev'd leaders.
Negs will be going into the dryer in another few minutes. I will have a report after they dry.
Report: snip test shows excellent leader density. Negs, not yet dry, look excellent also.
The only substances that I have ever seen mentioned are iron and copper ions. Years ago there was a long discussion on pure-silver on the Fenton reaction. This was when Ryuji Suzuki was formulating his developers. At the time he used salicylic acid (which chelates iron) in combination with TEA (triethanolamine which chelates copper) due to the unavailability of other chelating agents. Not everyone can use a ton of DTPA.
Is there anything remarkable about the container that the Kroger water arrives in, or that you are using to store it?
It would be most interesting if the chemists among us post their take on how much oxygen diffuses into water. Let's assume the container is more than permeable -- make believe it's uncapped and open to the atmosphere. If boiling drives out all/most oxygen, at what rate would it return? What's the forcing function(s)?As noted in earlier posts, most DW containers are made of HDPE plastic which is gas permeable and readily absorbs O2 from the atmosphere...
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