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 is an absolute requirement.
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.Basically the change in pH from base to acid literally squeezes all the developer out of the emulsion. This means the stop bath not only neutralizes the developer it rids the emulsion of the chemical as well, to make room in the emulsion to absorb your fixer.
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.
Stop bath is an absolute requirement. Basically the change in pH from base to acid literally squeezes all the developer out of the emulsion. This means the stop bath not only neutralizes the developer it rids the emulsion of the chemical as well, to make room in the emulsion to absorb your fixer.
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.
B&W film roller transport processing machines go straight from Developer to Fixer
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.
Stop bath is an absolute requirement. Basically the change in pH from base to acid literally squeezes all the developer out of the emulsion. This means the stop bath not only neutralizes the developer it rids the emulsion of the chemical as well, to make room in the emulsion to absorb your fixer.
I do not use acid stop for PMK film process, but I always do acid stop bath for silver printing. Try doing a lith print or solarization print without a good immediate stop, you will end up pulling out all your hair.. In my case I have lost most of my hair but you get the drift.
Don't worry; it's not critical and 1.5% w/v is certainly not a problem per se.I wonder if it not too strong ?
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 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.
P.S. He is using stop bath now.
This kid thinks we're a buncha geeks
I declare that stop bath represents the Old Church and water the Reformation.
"Here I stand, I can do no other."
- Martin Luther Roast
Oh good. Now this thread has at least another year of life
We're discussing DR5 reversal processing elsewhere; I think someone should print a list of all the steps in the process and nail that to the closest community darkroom door.
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