maddoc
... likes film again.
Any data about the change in developer concentration in the film emulsion when pouring out the developer and filling pH neutral water into the tank? Old films with a higher silver content and thicker emulsions might have been more effected as compared to to modern BW emulsions when not using a proper acidic stop bath.
Mark Wood
Well-known
Apologies, this is a bit "chemical" but it's important to get chemistry right. Permanganate is used in B&W processing for removal of silver, it isn't a pH indicator. It's the active constituent of one formula of "reducer" for reducing the density of over-exposed negatives for example and in the bleaching step in B&W reversal processing:
http://www.ilfordphoto.com/Webfiles/20061291034093.pdf
Ironically, although it's called a "reducer" in this context, it's actually acting by oxidation (the opposite of the actual chemical process of reduction!), which is pretty much all that manganese can do in its highest, +7 oxidation state in permanganate. In very dilute solution, where it will destroy silver more slowly, it can be used to oxidatively remove "hypo" (thiosulfate), according to the formulae in the old British Journal of Photography Almanacks.
The indicators in acetic acid-based stop baths are simple acid/base indicators, organic molecules that change their chemical structure reversibly, depending on whether they're in acidic or alkaline solution. This change in chemical structure simply changes the wavelength of visible light they absorb and so they change colour with pH. It's clear from the safety data sheets that Kodak have changed the indicator over the years but both examples in the earlier posts are just variations on the same chemical theme. Permanganate can't be used in this context.
roscoetuff
Well-known
Okay... to be clear, my desire to "save time" has nothing to do with development time and all to do with mixing time. One less mix is one less thing to do. Would agree that it's not about cost.
But the assumption is that using TF-5 wouldn't otherwise do anything adverse to the images. Something to gain and nothing to lose. I've been using Ilford's Stop Bath (Ilfostop?), and nothing wrong with it.
I'm now a little squishy and more confused that when I started the inquiry as to what effect shifting from Ilford's Rapid Fixer to Formulary's TF-5 will have and how it will affect the image as well as the process times. Sounds as though the Development time should shorten by 30 seconds in order for a water bath to purge the chemical, but since it won't actcually stop the Development until the TF-5 goes in, this would be an adjustment that encompasses that issue? Also sounds as if TF-5 will have a shorter life than Ilfostop in terms of rolls processed. Is this the right take-a-way?
But the assumption is that using TF-5 wouldn't otherwise do anything adverse to the images. Something to gain and nothing to lose. I've been using Ilford's Stop Bath (Ilfostop?), and nothing wrong with it.
I'm now a little squishy and more confused that when I started the inquiry as to what effect shifting from Ilford's Rapid Fixer to Formulary's TF-5 will have and how it will affect the image as well as the process times. Sounds as though the Development time should shorten by 30 seconds in order for a water bath to purge the chemical, but since it won't actcually stop the Development until the TF-5 goes in, this would be an adjustment that encompasses that issue? Also sounds as if TF-5 will have a shorter life than Ilfostop in terms of rolls processed. Is this the right take-a-way?
x-ray
Veteran
I've used Formulary fixers for years TF 4 and 5.
No, do not shorten your time. Water reduces the concentration of developer so quickly it's not necessary. I never have deviated from my process times with sheet or roll. Do not use acid stop! Formulary fixer TF5 has a high capacity for the number of rolls or sheets fixed. You'll have no less capacity than Kodak rapid fix. Both Formulary fixers are the preferred fixers for archival processing. They wash out of your film or paper faster and more complete than conventional acid fix. I use it for both film and fiber base paper. I use my once used paper fixer for film until it's depleted which takes quite a bit of film. I don't use my film for paper because of antihalation dye that come out of the film in the fix. It can stain your prints. Be certain not to over fix. Follow the recommended times because it's very fast and can bleach film and prints. IMO it's the best fixer on the market.
No, do not shorten your time. Water reduces the concentration of developer so quickly it's not necessary. I never have deviated from my process times with sheet or roll. Do not use acid stop! Formulary fixer TF5 has a high capacity for the number of rolls or sheets fixed. You'll have no less capacity than Kodak rapid fix. Both Formulary fixers are the preferred fixers for archival processing. They wash out of your film or paper faster and more complete than conventional acid fix. I use it for both film and fiber base paper. I use my once used paper fixer for film until it's depleted which takes quite a bit of film. I don't use my film for paper because of antihalation dye that come out of the film in the fix. It can stain your prints. Be certain not to over fix. Follow the recommended times because it's very fast and can bleach film and prints. IMO it's the best fixer on the market.
Ronald M
Veteran
Yes acid will ruin TF$ TF5 fix as they are a base like film developer. Acids neutralize bases.
Plain water, two times.
Plain water, two times.