I've been doing something similar for a number of years, except I use bits of film leader to time how long it takes to clear the film, then I double that.
I've been doing something similar for a number of years, except I use bits of film leader to time how long it takes to clear the film, then I double that.Just continue to use the fixer until your hypo check drops indicate it is exhausted
It's funny because I have the feeling that the stop bath has very deep roots. Lets not forget that back in the old days, the gelatin emulsion wasn't as well hardened as it is today. We all know that an alkaline PH will help soften the emulsion. So if you have an already soft emulsion, (even though it isn't hardening) using an acidic stop bath would have benefits.... I must admit that with the advancements in chemistry, the use of the stop bath is not as important as it once was...
That reminds me there was once a young homemaker named Alice whose procedure for making roast beef included cutting a small piece from each end of the roast. When Alice's very young and curious daughter asked why remove the ends of the roast Alice replied that she learned the procedure from her mother, and that she would ask her mother at the next opportunity. Alice's mother had a similar answer, "I learned it from my mother." Alice then decided to ask her grandmother the same question the next time she would visit her at the rest home. The mystery was finally solved! Alice's grandmother, who was by then quite old but still had a good memory, replied "My Dear Alice, when I was a young bride my roasting pan was too short to fit the whole roast, so I had to cut the ends off the roast to make it fit the pan."
I re-read your example. Why are you bothering to use carry over developer molecules? Why not just say, as in your example, out of 500ml of developer, you will have 5ml of carry over developer, or 1%. 1% ain't much, so nothing to worry about. That seems to be the essence of your argument. All that carryover developer molecules stuff is just unnecessary window dressing.
Query: what are your scientific credentials, particularly in the field of chemistry?
I take it that you think Kodak scientists asked their mothers whether they should recommend using stop bath, and that using stop bath is just an old wives tale.
My PhD was in chemistry, with physical chemistry emphasis. I spent my career working in the fields of physical chemistry, instrumentation development, and clinical chemistry.
I framed my example in terms of developer molecules because much of the previous discussion about developer carryover seemed to be framed in terms of carryover of developer, meaning the developer compound itself. However, it could be that carryover of alkaline buffer is what is detrimental to the fixer, not the developer molecules themselves. In any case, the same discussion pretty much applies to buffer molecules as well because by the time the carried-over buffer molecules reach the fixer they will be diluted by a huge factor and will probably be too few to matter because the acid in the fixer will overwhelm the week effect of the hyper-diluted buffer.
If the alkalinity of the carried-over buffer is indeed the potential problem then the carryover could produce a slow degradation of the fixer over a period of time, though I doubt degradation from that cause would be very noticeable. compared to fixer exhaustion by reaction of the fixer's thiosulfate with silver halide in the film.
Whos knows? Just speculating on a possible reason here, but more likely they just continued to use acid fixer when processing film because that's the way they always did it (and acid fixer may have once served a necessary purpose), but decades later they never got around to testing whether it was really necessary. They probably had more pressing projects to attend to, and if they would have found that water was good enough then it would have decreased the sale of one of their products.
In any case, if Kodak did investigate the issue then why didn't they ever publish the results? I assume that the results of such a study have never been published because no one posted here on the results of the investigation?
With respect to the first sentence of your response, I do not recall anyone referring to the "developer compound itself". The entirety of your response beyond the first sentence is a red herring.
So you think that PE just made up the tests he described back in 2017 in a discussion in which you were a participant?
Can you cite the post number for us so we can go back and read it? Also, where are the results of the study published so we can read and evaluate the actual results?
It was actually 2019. Here is the link:
Stop Bath.. How important?
RA4 colour negative print chemistry, is 45 seconds in the developer bath, then 45 seconds in the bleach/fix bath. Or 45 seconds in the developer bath, 15 seconds in a stop bath 15 seconds in a wash bath, 75 seconds in a bleach bath, 45 seconds in a wash bath, 45 seconds in a fixer bath, 90...www.photrio.com
Your post was #623 and his post was #624.
I do not know if the Kodak studies were published. Many manufacturers' internal studies are not published.
To add another variable to the discussion, in their Technical Data Sheet for Fomapan 100 Classic Foma says, "When the development time has elapsed, the film is recommended to be shortly rinsed in distilled water or dipped in a 2 % acetid [sic] acid solution for 10 seconds." It's the first recommendation I've seen for distilled water, which incidentally is what I use.
I dunno, how about post number 1164 by faberryman which seems to be framed in terms of developers? Though I admit that the post doesn't include the word "molecules"?
Additional note added: It is of course possible that I am mistaken about much of the previous discussion being framed in terms of developer carryover.
Here's another reference to using water as a stop bath: Phototherm used to make film processors. Their standard process used water as a stop bath. This can be found in the following link. https://www.phototherm.com/ssk4i.PDF. Here's the relevant line from that file:
WATER wash 2:00 23.9 5 also acts as stop.
No, I was quite straight forward, as was everyone else in the discussion. I was talking about developer, not developer compound.
Why would you rely on marketing material and instructions from a manufacturer of film processing machines over that of manufacturer of photographic film and processing chemicals. What about published studies from Phototherm?
You certainly seem to be grasping for straws.
If everyone employed a flowing water stop bath as completely and effectively as a Phototherm Sidekick processor does, there would be little advantage to using an acid stop bath.
Which component of the "developer" are you referring to? There are two components, developer compound and buffer. Which is it?
It doesn't actually matter, because, as I already discussed, for all practical purposes dilution affects both components the same way.
I am not referring to the separate components of the developer. I am referring to developer as a whole. The stuff you pour in the developing tank. You don't pour in or pour out the components separately. Nor do you carryover one without the other.
I know where you are trying to go with this. Let's cut to the chase, can the developer and buffer components, independently or together, be inside and outside the developing tank at the same time?
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