Is there value to an actual "acid stop" in my stop bath when doing C-41?

rpavich · Jul 19, 2016

I have been assembling the chems and procedure for doing ECN-2 and noticed that the directions I'm following call for a vinegar+water stop bath.

I have been doing C-41 with a water only stop but this made me wonder if there would be value to doing it with the vinegar+water?

RPC · Jul 19, 2016

A water-only stop with C-41 is not recommended. It will not stop development in the three emulsion layers evenly, if it stops it at all, and can cause crossover. If you use standard C-41 bleach you can go directly into the bleach and a stop is not necessary, although many use one. Vinegar plus water to form a 2% acid stop will work fine. Use white vinegar only, not the colored kind. A ferricyanide bleach would always require a stop.

rpavich · Jul 19, 2016

RPC said:
A water-only stop with C-41 is not recommended. It will not stop development in the three emulsion layers evenly, if it stops it at all, and can cause crossover. If you use standard C-41 bleach you can go directly into the bleach and a stop is not necessary, although many use one. Vinegar plus water to form a 2% acid stop will work fine. Use white vinegar only, not the colored. A ferricyanide bleach would always require a stop.

Well thank you very much for clearing that up!

I will definitely stop doing the water stop thing after development.

My workflow is:
water + Washing soda shake like the dickens to remove remjet. Wash several more times until the water is clear.

Dev 3m 15 sec

Water wash/stop

Bleach 3m

Water wash/stop

Fix 6m

Ilford washing routine

Remove residual Remjet via running water and microfiber cloth.

Stabilizer

Dry negs

Rudeofus · Jul 19, 2016

One more thing: Kodak's ECN-2 process manual suggests a stop bath made from Sulfuric Acid, not from Acetic Acid, see here on page 7-29.

iandvaag · Jul 19, 2016

Not to hijack this thread, but could I use sodium bisulfate for ECN-2 stop? I don't have access to sulfuric acid AFAIK. I've asked around and no one seems to have battery acid either. If I can't use bisulfate, I'll have to use an acetic acid + sulfite stop with an extended wash and hope for the best. (I'm using a ferricyanide bleach)

RPC · Jul 19, 2016

Just thinking, I thought the OP meant C-41 all the way, i.e., C-41 film in the C-41 process but if he meant ECN-2 film in C-41, then yes, sulfuric is used from what I have heard.

rpavich · Jul 19, 2016

RPC said:
Just thinking, I thought the OP meant C-41 all the way, i.e., C-41 film in the C-41 process but if he meant ECN-2 film in C-41, then yes, sulfuric is used from what I have heard.

I meant c-41 process for c-41 film. I only mentioned ECN-2 because I am going to be trying that process also.

RPC · Jul 19, 2016

rpavich said:
I meant c-41 process for c-41 film. I only mentioned ECN-2 because I am going to be trying that process also.

I began to wonder because in your workflow you listed remjet removal. C-41 has no remjet.

rpavich · Jul 20, 2016

RPC said:
I began to wonder because in your workflow you listed remjet removal. C-41 has no remjet.

That particular comment was in reference to the ECN-2 question but the workflow that I was wondering about when I posted the question was the C-41 which was just water.

darkroommike · Jul 20, 2016

A stop bath is a good idea for C-41 if you reuse your bleach and fix (or blix) so that the pH of your bleach doesn't change from developer carryover. A replenished line (with proper q.a. with a densitometer) doesn't have this problem since the bleach replenishment rate is high enough to handle the carryover and usually has some sort of arrangement to minimize developer carry over.

Is there value to an actual "acid stop" in my stop bath when doing C-41?

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