Longevity of stock TF-5 Archival Rapid Fix?

[Michael R]

Preferred why?

No earth shattering reasons. TF-5 is a little more convenient to mix into working solutions than TF-4 which has the gunk. And being close to neutral in pH means less odor for those who are bothered by either the usual acrid smell of acid fixers* or the ammonia smell typical of alkaline fixers. Other than that they do the same thing.

*As an example, for people sensitive to the smell of acidic fixers, Kodak recommended mixing a less acidic version of F-5 called F-6 in which the boric acid is omitted and sodium metaborate is added to raise the pH.

[Tin Can]

Art may use 'science' but science is not art

I am so happy I quit Physics age 21

and did not waste my life with all the shit they just denied

String Theory, Big Bang, on and on

I worked in Labs on applied science almost my entire life




I really did not want to help make better bombs

I knew how to make a nuke age 8 from the Library

[Michael R]

The obligatory “science is not art” mic drop. The last refuge of anyone who is neither artist nor scientist.

[Drew Wiley]

I recently switched over to TF5. It seems to be a worthy replacement to TF4 in every respect, but is actually a little cheaper, and it doesn't need to be aggressively stirred if the bottle has been laying around awhile. TF4 lasted quite well in concentrate. But I'll use my TF5 too soon to give a long-term answer about its storage life. No difference between them with respect to PMK pyro stain results.

[Sal Santamaura]

Preferred why?

No earth shattering reasons. TF-5 is a little more convenient to mix into working solutions than TF-4 which has the gunk. And being close to neutral in pH means less odor for those who are bothered by either the usual acrid smell of acid fixers* or the ammonia smell typical of alkaline fixers. Other than that they do the same thing.

*As an example, for people sensitive to the smell of acidic fixers, Kodak recommended mixing a less acidic version of F-5 called F-6 in which the boric acid is omitted and sodium metaborate is added to raise the pH.

Not too many months ago, after being a TF-4 user for decades, I tried a small bottle of TF-5 just to see whether it made any difference in the stain on PMK-developed Delta 100 negatives. None was detectable. Now that my last gallon concentrate of TF-4 is almost gone, even though I don't notice much difference in the odor, I'm considering TF-5 instead. However, an aspect of TF-4's alkalinity I always appreciated is that one can be cavalier about extended fixing times without concern about bleaching. Do you know whether the same applies to TF-5? Thanks in advance.

[Michael R]

Same with TF-5 or any fixer that is close to neutral or higher in pH. The rate of bleaching action of fixer is directly related to acidity, which is why it was something more important to watch out for when more acidic hardening fixers were the norm. Even Ilford Rapid Fixer would be much slower to bleach than older alum hardening formulas. At pH 6.5-6.8 (TF-5) it’s a non issue. If I remember correctly Ron even tested for it just to dot the Is and cross the Ts.

Not too many months ago, after being a TF-4 user for decades, I tried a small bottle of TF-5 just to see whether it made any difference in the stain on PMK-developed Delta 100 negatives. None was detectable.

Now that my last gallon concentrate of TF-4 is almost gone, even though I don't notice much difference in the odor, I'm considering TF-5 instead. However, an aspect of TF-4's alkalinity I always appreciated is that one can be cavalier about extended fixing times without concern about bleaching. Do you know whether the same applies to TF-5? Thanks in advance.

[Tin Can]

I always trusted Ron

[Michael R]

Definitely a good source, and always helpful in my experience. I went to him with lots of rather arcane topics/questions in my years on APUG/Photrio, and he was always gracious. His death was a blow.

I always trusted Ron

[Tin Can]

Just to remind

I count sheets to decide when to replace TF5

as it seems to never lose speed