I'm considering switching over to using glacial acetic acid, and was curious to the hive mind what sort of dilution ratio I would need to use for a stop bath for ECN2/C41 process? I want to keep things consistent, hence the usage of the glacial variety (instead of say, generic store bought vinegar)
Thanks!
Distilled white vinegar from the store is consistent at 5% dilution, and of a high purity considering that it is food grade. The only thing that glacial strength will gain you is time between having to get more. Also, as the growing season is about to start you might want to take a look in the pesticide and herbicide section of the garden centers. Last year at my local Walmart they had gallon jugs of 30% acetic acid (marketed as 30% "vinegar") as an environmentally friendly herbicide and insecticide. Quality on the label doesn't indicate any impurities, and I haven't seen any detrimental effects on my negatives.
The only thing that glacial strength will gain you is time between having to get more.
About 1% glacial acetic acid should be fine
I want to keep things consistent
If the acetic concentration is at 5% then it seems I need to use a 1:4 dilution ratioo, yielding 120ml acid + 480ml water to achieve my 600ml final volume. Is my math correct?
Would I be able to use this ratio for 10 rolls?
Vinegar I suppose can down the drain, but once its used as a stop bath its not clear to me.
acetic acid is not strong enough
What goes wrong if you use acetic? I've not noticed any ill effects so far.
PS: I use a PDTA bleach, not ferricyanide, with ECN2 films, if that matters.
Would you have a formula for PDTA bleach
There are formulas on Photrio, but I simply use Fuji bleach.
I remember Photo Engineer said that a sulfuric acid stop bath is a requirement for ECN-2, because it's necessary to form the correct dyes. Without it, the dyes may not be stable and archival.
This is what he said to me when I inquired after it. The argument boils down to (1) getting rid of the developer, and (2) "my colleagues knew what they were doing so let's assume there is a reason". The extraction argument I believe should be seen in the context of high-volume machine processing, where the dwell time of the film in the stop bath is brief. In a home setup, you can easily extend the stop bath time and follow it with one or two rinses if so desired. I suspect that this ultimately achieves the same stability.Sulfuric acid is stronger than Acetic. If it were Acetic, I really think Kodak would let us know. And the reason is to extract all of the CD from the film with a strong acid bath which thus gives better dye stability.
Sometimes, Ron was just like the rest of us. He passed on what he remembered, informally so, and while is knowledge was encyclopedic, it was not absolute, infinite or infallible.I was taught to never use a citric acid bath as a stop for some reason. I knew it at the time, but over the years it has never come up until recently.
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