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Alkali Fixers - The Myths & Legends

Ian Grant

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Over the past 7 or 8 months I've been looking at various fixers, Alkali and Acid.

So far I've not found any conclusive research that shows Alkaline fixers are actually beneficial for B&W processing.

I have found people who have used densitometry etc to show mildly acidic (pH 5.2-5.5) fixers like Hypam/Ilford Rapid fixer have no detrimental effect on negatives developed in Pyro developers (Pyrogallol & Pyrocatechin).

But I can't find any evidence that they genuinely reduce wash times either.

So can someone point me to the research findings ?

Ian
 
Ian;

No published findings that I know of except for the work by Haist and work I did at EK which is for the main part unpublished. I can back up most of the assertions on alkaline and neutral fixes as well from work I have personally done. As pH goes up, swell goes up (with bone gelatin) and washing becomes easier. As pH goes down wash slows down until you get to pH 4.5 where washing is most difficult.

As pH goes up, stability goes up, as pH goes down, stability goes down until you can actually destroy fixer instantly by adding a drop too much acid.

As pH goes down, you can add swell inducers to counteract the effect of the pH on swell and get more rapid washing.

I have verified this both at EK and at home, but remember that these are generalities and apply to bone gelatin, not pig gelatin. IDK about Yak gelatin.

PE
 
I've held off from mixing my first pack of PMK pyro 'cos I've not got a fixer with 'suitable' pH, so would be very interested in finding out if the stain won't disappear upon contact with my Ilford Rapid...
Simon
 
What about the Llamas

But if you use a HCA you over-come the swell/shrinkage issue anyway, perhaps this was why Agfa recommended Sodium Carbonate as the HCA for their Fibre based papers.

I can see there's a definite problem with acid hardening fixers at pH 4.3, but then something like Hypam at pH 5.3 shouldn't be much of an issue. I've seen the pH of TF-4 reported to be 6.5, hardly alkaline !!!

Ian
 
Gee, Ian, what prompted this question?

I give up---I'm just going to accept that I don't understand anything, and sit back and wait for you experts to sort it out! (Personally, I'm more concerned about the washability than the putative pyro problems.)

-NT
 
At any pH from about 6 - 9 a wash aid is often not necessary as the wash speeds up so much due to swell. It depends a lot on water supply (hardness) and paper or film hardness as well as the thickness of the coated layer. That is why I suggest testing to everyone to establish their best position.

PE
 
So your saying that a fixer of say pH 5.3 will be fine then, after all as soon as you start washing the pH will change. But then wash aids aren't just about gelatin swell and are used to tip equilibrium balances, particularly of the partially soluble silver-thiosulphate complexes. But we could help the water supply by ensuring it's mildly alkaline early in the cycle ?


Nothing you've said/written Just something I'm curious about, as all the hype about TF-4 seems contradictory.

Ian
 
I've found that water hardness is more significant than pH when it comes to water supply, but again that is a generalization. Wash aids can actually decrease swell due to the salt effect if concentration is off. Too high and swell goes down.

The silver thiosulfate complexes (about 5 of them) are huge, but the ammonium silver thiosulfate complexes are considerably smaler and there are other agents that can be inserted into the complex "cage" to change ionic attraction, size and diffusion rate. Thiourea comes to mind here. It is smaller than thiosulfate and so like ammonia can increase diffusion rate and also it is synergistic with hypo increasing fixing rate. Being non-ionic, thiourea helps in other ways too. Or at least it changes the playing field.

So, there is no one answer Ian. There are many many doorways and mirrors all over this room. Many of them do NOT lead to wash aids of any sort. And that is a very important point. I can increase wash rate by about 50% just by manipulating the fix, and this is in comparison to TF-4.

PE
 
I've measured the pH as 8 for fresh TF-4.
 
alk fixers

my personal experience tells me that TF4 is waaay overated....been using it lately and not all that impressed....even gives off a weird smell after fixing
give me a good powder anytime that I can mix fresh
Best, Peter
 
Peter Schrager said:
my personal experience tells me that TF4 is waaay overated....been using it lately and not all that impressed....even gives off a weird smell after fixing
give me a good powder anytime that I can mix fresh

Best, Peter
Click to expand...

This is what others have said as well, that doesn't mean it's a bad fixer, just that the so called advantages are over hyped, and it may well have no real benefits compared to say Hypam/Ilford Rapid Fixer or another equivalent.

Ian
 
The odor is very weak ammonia due to pH and ammonia. The major benefits in TF-4 are in the wash rate. Of course, it keeps very well too. I have kept it at least 2x - 4x longer on the shelf as concentrate and as working solution than any other fixer.

PE
 
I use TF-4. I'm no photochemist, but I like the longevity of it, and I like the short wash times that it permits. It lets me avoid a wash aid step, and saves me significant washing time (which is also pretty environmentally beneficial).

Yes, it stinks. So do acid fixers; I'm not that fond of the smell of acetic acid.

I can also forgo a stop bath step since the developer will not deleteriously affect my fixer's pH. I use plan water instead.

Sure, TF-4 is a little more costly but it is not ridiculous. The price of the film is a lot more significant than the price of the photochemistry.

I started using it because I use PMK a lot (and I still do) but I've come to use it for all of my film processing. I haven't yet used it for paper processing (particularly for RC since the wash times are already so short) but I might adopt it for fibre paper at some point.

If you don't feel that alkaline fixers add value to your processing, feel free to use acid fixers. I won't mind.
 
I am now able to formulate an odorless, high speed fixer that has long shelf life. It uses the same wash cycle as TF-4. Bill Troop and I did the work on this.

I am also able to formulate an odorless, high speed fixer with long shelf life that just about cuts the wash cycle in half.

Both of these can work with a stop bath, and BTW - TF-4 works well with a stop bath too. I've tried it and proven it to myself. Beware that all alkaline fixes can fail if you don't use a running water rinse after the developer. The development does not stop properly and the fixer goes bad faster due to carryover as the standing rinse seasons in with used developer.

PE
 
Last edited by a moderator:
Jim, you surprise me wash times with films are always fairly short, much the same as RC papers, so the benefit should be far greater with paper which needs more water.

I haven't seen anyone recommending significantly shorter wash times than Ilford suggest with Hypam/Ilford Rapid Fixer, and as tests show no difference compared to Hypam with PMK and other Pyro developers something doesn't quite stack up.

I'm trying to find the scientific evidence not the myths, however I am willing to accept that sometimes the unproven is true. I had a Virology lecturer back in 72/3 who said many cases of cervical cancer were caused by a virus, we know & are sure it's true but we just can't prove it, it was 20+ years before the proof was found & accepted.

If I still had access to an AA-spectrometer I'd do some tests of papers fixed in different fixers Alkaline & Acidic after different wash times, I've no idea what happened to the Varian AA machine I bought 14 years ago but it sat idle for quite a long time. It was accurate to a few PPM. (parts per million).

We used it to test for precious metals mainly for the jewellry trade, Gold, Silver, Platinum & Palladium as well other constituents in Jewellery, but we had a vast array of tubes for most other metals.

Photo labs used us to test fixers, & bleach fixes, and the results we reported would be far higher than the refiners claimed was in the solutions, but then I've worked on both sides, so know what really happens The irony was we tested for both sides

Anyway despite all that I'm still struggling to find any accurate information on the benefits of an alkaline Fixer like TF-4 compared to developers like Hypam.

Ian
 
Peter Schrager said:
my personal experience tells me that TF4 is waaay over
rated....been using it lately and not all that impressed....
even gives off a weird smell after fixing give me a good
powder anytime that I can mix fresh Best, Peter
Click to expand...

Like to stay alkaline? Try TF-2. All dry components.
They last and last. Easy Home Brew. Likely no odor.
I use just the thiosulfate of the formula and know no
odor. The thiosulfate alone makes for a very near
neutral fix. Just enough for the session is mixed.
I use it very dilute one-shot. Works well with
my single tray method of processing. Dan
 

Any chance of these becoming available at some point, or of publishing the formulae?
 
TF2

OK Dan you got me....what is the formula for TF2?? is it in the cookbook? I'll go look now....for papers I use the michael smith fixer formula....it's way cheaper to buy 25 pounds of NaThiosulfate and add the bisufite fresh for the printing session....have never had any problems with washing; staining;etc.
obviously I make a lot of prints but cost wise it makes sense to me
Best, Peter
 
I wonder if there are any detrimental effects with increased alkalinity - for instance, as you increase pH from about 6 to about 9. PE has mentioned increased emulsion swelling, which probably corrects itself after drying, but I'm not sure what other effects this and anything else that happens may have.
 
Use of pH values above 8 should use a hardener fix. At pH 9 or above, swell becomes so great that you risk reticulation. At that point, Kodak used Alkaline Hardener Fix (AFHF) or Alkaline Formalin Hardener Fix.

PE
 
Photo Engineer said:
Thiourea comes to mind here. It is smaller than thiosulfate and so like ammonia can increase diffusion rate and also it is synergistic with hypo increasing fixing rate. Being non-ionic, thiourea helps in other ways too.
Click to expand...

Thiourea, even though it has a long history with toning, is a chemical I try to avoid. It has a Contact Rating: 3 - Severe (Life). It is anticipated to be a carcinogen - in response to that the State of California has declared it to be carcinogenic.

Probably best to avoid the use of it if you can.
 
BTW, about the stop bath, for FB printing, I happen to use a buffered one (pH +/- 5,5) in combination with a two bath C-41 fixer (FUJI's Unilec pH +/- 7,5). The first fixer bath goes down to pH 6 à 6,5 after a while, but the second one stays at around pH 7. As a HCA, I just plunge the paper, after a short wash, in 2% Sodium sulphite for 2 min. before I process it in KRST 1:10 for an other 2'. No problems so far.
I think that a buffered stop has more 'respect' for a neutral to alkalic fixer. And the stop bath can be replenished by topping off, and this kind of fixer lasts longer too, so less dumping into the environment. This, of course, does not mean that this is a match better way of 'acting' nor is it the Holy Grail, but worth considering, does it?

Philippe
 

The TF-2 formula:
Sodium thiosulfate-sulfite-metaborate, 250-15-10
grams. Water to make one liter. Likely in the cookbook.
Similar to Adam's plain fix save for the metaborate. That
250 is the penta hydrate; 160 for the anhydrous.

Additions of bisulfite will lower the ph. The Michael Smith
formula? What might that be? Dan
 
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