Go read the preceding 1300 comments. It's not a requirement for film at all and it's only marginally beneficial for rc paper. It's a "requirement" for fb paper - particularly porous fb paper (like Ilford Art).
Stop Bath.. How important?
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Go read the preceding 1300 comments. It's not a requirement for film at all and it's only marginally beneficial for rc paper. It's a "requirement" for fb paper - particularly porous fb paper (like Ilford Art).
Welcome to Photrio! There's some merit to this very simple and clear way of putting it. It also aligns well with what @Photo Engineer (RIP) said in the past about ECN2 stop bath needing to be very acidic for this specific reason.
Whether stop bath is an 'absolute requirement' - well, we've not quite been able to figure that one out in 20 years. Let's see how we stand on the matter by 2045.
Yes. Use stop bath!"On the long edges of each frame is a subtle area of increased density which runs the length of the frame. "
It's very hard to say definitively. There can be some excess density added around the sprocket holes with over-agitation. The developer slows in handout through the sprocket holes more than across the rest of the film.
STOP BATH VS WATER: This is pretty obvious, but here goes: Stop bath "stops" the developer action with a chemical reaction which is essentially instantaneous. Think baking soda and vinegar, instant action, also bubbles formed by the chemical reaction. If the acid-base reaction is strong enough - you put in too much stop bath (too strong), then bubbles can form and pop the emulsion right off the film base. I've used plain developer temp water, which stops the development by dilution, fill, shake, dump, and you are probably OK but if you want, do a second fill, shake, dump, just a few seconds is all you need.
Someboddy's gonna take exception to this, probably, but I've been processing film since the mid-1960's and owned a camera store which did enormous amounts of processing of all sorts, including a well-equipped b/w darkroom operation, that's how we did it, nearly fool proof.
***** I received the info from a friend, and assumed it was 'current'. Joke's on me, I guess. OH well, no matter, answer's still the same. Thanks for pointing out my delayed response.-)
BTW: It would be good to see a sample of what the problem looks like, that may help more than 1000 lines of text in reply.
Can you elaborate please? I can't imagine how this works
MattKing
Moderator
If you are running film high speed through something like a roller processor, and process times are closely controlled and really short, something like stop bath is critical. For hand processing, there are other effective choices for film.
I use stop bath.
I use stop bath.
B&W film roller transport processing machines go straight from Developer to Fixer, there's no Stop Bath or Water Rinse. I had to point this out to Ron Mowrey (PE) quite early on in this thread, that is the case with Fuji, Ilford and Kodak machines at the time, They had no option for a Stop Bath.
Ian
OTOH, they don't try to be "gentle" with their film and use a pretty acidic fixer, which acts as an effective stop bath in itself. Most of us don't do it that way, but when you're replenishing the fixer you can compensate for the pH change due to carried-over developer.
Ilford 2000T fixer or Hypam is no more acidic than Ilford or Kodak Rapid fixers, it's probably better buffered though. pH5.0 - 5.5 is not as an aggressive shift compared to an Acetic acid stop bath which is typically pH2.5 - pH3.6, or a Citric Acid stop bath at pH 2.6 - pH3.8, neither of which have a detrimental effect on negative quality.
Going from Developer straight into Fixer greatly increases the risk of Dichroic fogging, which is why we must always use a Stop bath, or as manufacturers suggest alternately a water rinse with films. However with a roller transport processor the film goes through rollers and there is virtually no developer carry over into the fixer, which is circulating rapidly, so Dichroic fogging never occurs.
Processing in tanks or drums we carry over developer into stop bath or rinse water, so we are relying on neutralising, or highly diluting developer.
Ron Mowrey earlier in this thread mentioned you must use a Stop bath not a Water rinse if using an Alkali fixer. In his testing with a Water rinse he found it took too long for the fixer to neutralise residual developer in the emulsion, and he sometimes had Dichroic fog formed. Most "Alkali" fixers are actually mildly acidic around pH6, TF-4 is pH5 conc, according to its MSDS.
Ian
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I would like to see the scientific papers that support this theory.
That's what I found the hard way as some were total fails doing Lith printing as a majority of my Pyro developing in water only for stop.
I use 15g / 1000ml of citric acid nowadays for both films and papers and haven't got any problem, but I wonder if it not too strong ? I sometimes see this recipe used 1:1 so I'm wondering..
Developers are either XTOL or HC-110 for films and Adox Neutol eco pro (ascorbic acid based) for papers.
Developers are either XTOL or HC-110 for films and Adox Neutol eco pro (ascorbic acid based) for papers.
Don't worry; it's not critical and 1.5% w/v is certainly not a problem per se.
The main 'risk' with a stop bath with a very low pH is that sulfite carried over from the developer will escape in the form of sulfur dioxide gas. This has a pungent smell and some people find this obnoxious or even unacceptably irritating. If you find this to be a problem, consider mixing a buffered stop bath to avoid this altogether. https://www.photrio.com/forum/threads/buffered-citric-acid-stop-bath.201215/
From a viewpoint of the film or paper, a low pH is not a problem, at least not for modern emulsions. 15g citric acid to a liter is also well within the safe zone, regardless.
it's refreshing to know stop-bath conundrum is well and kicking like never before.
I don't use it. I want to give all chemicals equal opportunity to work, act, and then get out of town to make space for the next one. Letting them fighting it off has seemed to work for me just fine. But yes I do rinse religiously in between. No just fill & drain, it's fill/spin/invert/drain ... a few times.
I don't use it. I want to give all chemicals equal opportunity to work, act, and then get out of town to make space for the next one. Letting them fighting it off has seemed to work for me just fine. But yes I do rinse religiously in between. No just fill & drain, it's fill/spin/invert/drain ... a few times.
OK, thanks !
Long after analog photography is no longer used by anyone, Photrio will exist to debate film prewash, stop bath, and stand development
I wonder what the longest running thread here is.
If you count the original plus the current one, probably the "most recent purchase" thread in Miscellaneous Equipment.
Or "What are you listening to"
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