Same stop bath for first dev and colour dev (E6)

athbr · Jun 4, 2019

I'm attempting to scratch mix E6 chemistry due to general unavailability of kits in my country.

Because I don't have running water in my darkroom I am hoping to use a stop bath (citric acid fwiw in case that's important) throughout the process when water is needed (excluding the final rinse, of course).

So basically: FD -> Stop -> CD -> Stop -> Fix -> Bleach

My question:

Can I use the same stop for both parts?

Will it lead to any immediate deviations from intended results or will it just mean my fix doesn't last as long?

I can deal with the latter as I'm only mixing enough for 5 rolls at a time and dumping straight after.

thanks.

koraks · Jun 5, 2019

I recall @Photo Engineer saying that citric acid should not be included anywhere in a color process. I'm not sure why, and I personally do use it in RA4 processing with no apparent I'll effect. But to be sure I'd just use acetic acid. And I don't see why the same stop could not be used in both places of the process - but then again, given the minimal cost of acetic acid, I don't see a clear advantage in reusing the stop.

Anon Ymous · Jun 5, 2019

athbr said:
...So basically: FD -> Stop -> CD -> Stop -> Fix -> Bleach...

I suspect you know it, but you first bleach, then fix. Regardless of that, I've never used a stop bath in E6 processing, but only washed between these stages. 5-6 water changes with 30 vigorous inversions each time is all I've done. It worked fine. Having a large bucket (or buckets) of hot water is all that is needed. Start with a water temperature slightly above the processing temperature, it's not very critical anyway. The most critical stage, time and temperature wise, is the first development, the rest have fairly large tolerances.

bstark · Jun 5, 2019

Going directly from stop to CD is likely to ruin the CD by altering the pH. Stop after FD will introduce colour shifts relative to a water rinse, so better stick with water rinses.

Photo Engineer · Jun 5, 2019

A stop after FD is not indicated, but can be used if the color shift is not unreasonable. Some use it due to their water being unsuitable for the wash. The bleach is used before the fix. A reversal step is used between the FD and CD as follows: FD > (optional stop) > Wash > Reversal Step > CD > (optional stop) > Bleach > wash > Fix > wash > Final Rinse.

PE

athbr · Jun 5, 2019

Anon Ymous said:
I suspect you know it, but you first bleach, then fix.

Yes this is a mistake, thanks for catching it.

Wasn’t aware a stop bath could lead to colour shifts. Back to the drawing board for a minute, I guess.

Luckless · Jun 5, 2019

One useful reason to not use the same bath more than once in a manually run process is to help avoid ordering issues:

A to B to C to D to E... with a single step using a single tray/cup/bottle that exists in a single spot in your work area greatly helps reduce the risks of getting out of order. It then becomes much harder to either skip ahead to something or to 'go back' to the wrong chemical by mistake.

- Line everything up in order before you start, and run things down the line, in order.

athbr · Jun 5, 2019

Luckless said:
One useful reason to not use the same bath more than once in a manually run process is to help avoid ordering issues:

A to B to C to D to E... with a single step using a single tray/cup/bottle that exists in a single spot in your work area greatly helps reduce the risks of getting out of order. It then becomes much harder to either skip ahead to something or to 'go back' to the wrong chemical by mistake.

- Line everything up in order before you start, and run things down the line, in order.

Touche. But just to add context:

I’m trying to create an automated dev machine using arduinos. Things are going well but still early.

Either way, confusion of this sort won’t be an issue. But reducing the number of tanks and pumps and solenoid valves needed is always a plus.

So figuring out the minimum viable process is important in this case. So stop was one place I’d imagine. Another is blix but I also hear mixed things about that.

I’ll probably have to do a number of manual tests and decide what kind of complexity/quality trade off I can live with.

koraks · Jun 6, 2019

athbr said:
using arduinos

A bit off topic perhaps, but you may look into ESP8266 based boards like the Wemos D1.

Rudeofus · Jun 6, 2019

The step sequence "FD -> Stop -> CD" is also problematic, since it carries FD into CD. Since CD is very alkaline, even traces of FD will become very active and act as competitive developer, leading to density loss. That's the reason why there has to be a wash cycle between FD and CD.

Even the most aggressive step sequence for E6 that I am aware off (coming from Kodak's 5l E6 kit to be used single shot: FD-->wash-->CD-->prebleach-->bleach-->fix) has this one wash step, so it appears to be absolutely essential.

Photo Engineer · Jun 6, 2019

Basically, the wash after the FD serves a variety of purposes.

It just about stops development from the top down and thus the bottom layer has just a tad more chance to develop. Since this varies with water supply, I have never been a big fan of this method. It also serves to prevent carryover of FD into CD. And it also serves to be a holding bath for light reversal if that is your method of choice.

For those who think this is an argument against stop baths, I disagree. Stops are good but this is the way EK chose to go and it seems to work for this process due to the high temp, compared to the 20C process used for B&W.

PE

athbr · Jun 6, 2019

Rudeofus said:
The step sequence "FD -> Stop -> CD" is also problematic, since it carries FD into CD. Since CD is very alkaline, even traces of FD will become very active and act as competitive developer, leading to density loss. That's the reason why there has to be a wash cycle between FD and CD.

Even the most aggressive step sequence for E6 that I am aware off (coming from Kodak's 5l E6 kit to be used single shot: FD-->wash-->CD-->prebleach-->bleach-->fix) has this one wash step, so it appears to be absolutely essential.

Thanks for this. This is quite a compact process. Naive question but what is prebleach for? Could you do CD->bleach->fix or am I asking for trouble?

athbr · Jun 6, 2019

koraks said:
A bit off topic perhaps, but you may look into ESP8266 based boards like the Wemos D1.

I've been prototyping with a few unos. it's going quite well!

But why do you advise ESP8266? I guess it would be nice to be able to track the progress from my computer/phone. But I've been promising myself not to let feature creep happen this time. But then again I said that last project I did so who knows.

Rudeofus · Jun 6, 2019

athbr said:
Thanks for this. This is quite a compact process. Naive question but what is prebleach for? Could you do CD->bleach->fix or am I asking for trouble?

Since Ammonium Ferric EDTA is a very mild oxidizer and E6 film is not qualified for stronger bleaches, a well defined amount of bleach accelerator must be brought in to ensure complete bleaching in an acceptable time frame. Too little or too much bleach accelerator would cause bleaching action to become very slow or incomplete. Prebleach brings in this accelerator through carry over, which is the most reliable method for getting a small but well defined amount of bleach accelerator into the bleach.

Prebleach with its sulfite also makes sure, that the bleach can't oxidize the color developing agent, which in turn would form additional unwanted dyes.

Finally prebleach contains Formalin, which deactivates unused color couplers, thereby making the final image more stable (c.f. Photo Engineer's sticky thread on color stabilizers).

If you look at three bath kits, which do not ask for a prebleach: they contain the bleach accelerator in the BLIX bath (much less capacity, therefore bleach accelerator won't get used up), they require a long water wash between CD and BLIX, and (at least the good ones) contain Formalin in the final rinse bath.

Photo Engineer · Jun 6, 2019

And don't forget the reversal step if a reversal agent is not included in your process.

PE

mshchem · Jun 6, 2019

I loved reversal exposure with E3. I remember being terrified that (being warned by EK) that I would drip water onto the hot No 2 Photoflood and shatter the bulb. No bottles back then. I used 1/2 gallon Mason jars with rubber gaskets and metal/glass lids. .
Last time I was playing with reversal exposure I used a LED flashlight .

Photo Engineer · Jun 6, 2019

I did the same, with Mason jars. Oh my. I dropped and broke the bleach and sopped it up with a sponge to finish my roll of Super Anscochrome.

PE

koraks · Jun 7, 2019

athbr said:
I've been prototyping with a few unos. it's going quite well!

But why do you advise ESP8266? I guess it would be nice to be able to track the progress from my computer/phone. But I've been promising myself not to let feature creep happen this time. But then again I said that last project I did so who knows.

It's a nifty device; apart from inboard WiFi it has all the memory you'd likely need, easy setup of SPIFFS and more importantly it allows interrupts to be attached to any pin and any pin can be used for PWM. Combined with the price which is barely higher than 3rd party Arduino-compatible boards (and much cheaper than genuine Arduino), I find it a very attractive proposition.
For the project I'm currently working on I opted for a Nano-type board due to its larger number of GPIO pins, but to some extent I regret not having solved this with a few 23017's.

Rudeofus · Jun 7, 2019

Photo Engineer said:
And don't forget the reversal step if a reversal agent is not included in your process.

You are correct, I forgot that in my process sequence, too. It should be FD-->wash-->reexp-->CD-->prebleach-->bleach-->fix.

Same stop bath for first dev and colour dev (E6)

athbr

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Same stop bath for first dev and colour dev (E6)

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