Fixers: acid vie alkaline

Trevor Crone said:

Just to clarify from a personal point of view I've only carried out a visual comparison with Peter Hogan's alkaline and Fotospeed's acid fixers with 4x5 T-max 100 developed in PMK pyro and I could not see a visual difference as to the amount of stain. They looked the same to me.

While I have used Peter's excellent Prescysol developer I have never done a comparison with this developer. Peter clearly states on his website that his alkaline fixer preserves the staining effect.
http://www.monochromephotography.com/fixer.htm
The effect may indeed be apparent with different films/developers it would be nice if someone could carry out a comprehensive test with various films/staining developers.

Regards,
Trevor.

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IMO (my opinion is based on my own laboratory experience) to evaluate image stain you need a transmission densitometer with the proper spectral sensitivity. Visual evaluation can produce very misleading results.

Tom Hoskinson said:

IMO (my opinion is based on my own laboratory experience) to evaluate image stain you need a transmission densitometer with the proper spectral sensitivity. Visual evaluation can produce very misleading results.

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Tom, I certainly agree visual evaluation can be misleading, but what was important to me, I saw no clear advantage in printing my pyro developed TMax negs. fixed in an alkaline fixer with negs. fixed in an acid fixer.

Obviously to perform a fair test one whould have to produce two sets of negatives exposed at the same time, lighting and subject matter, then developed in the same developer for the same time, agitation and temperature. Then of course split between the two types of fixer. Other films and staining developers would need the same fair tests. This would be quite a time consuming adventure, something I haven't got time to do at the moment. But it would be interesting to see if there are 'real' differences with regard how a finished print would look.

Regards,
Trevor.

BobNewYork said:

I tend to buy mini-lab C-41 fixer and use that. The container just lists ammonium thiosulphate - shouldn't be a problem; should it?

Bob

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Not a problem Bob. I've been using Kodak's Flexicolor fixer for C-41 for a couple of years now. Works great and it's fast, as you know. PH is close to neutral, about 6.5 at working strength.

Dave. If you await my experiment you may be playing the harp or stoking before you get the results! I certainly second the idea of some stalwart such as Leon giving it a go. It's the prints that are the clincher either way.It's precisely that sort of article that would make me buy B&W mag. I do now most months anyway but I give a committment here and now to buy B&W mag when this article is there.

Just one further thought. It may be that Peter Hogan did the experiment himself and has the evidence and could cobble together an article for B&W.

Everything I hear about him suggests that he recommends his alkaline fixer for sound reasons but it would be nice to see an article on it.

pentaxuser

Steel wool will work to remove silver from all fixes, and the standard tests for silver retention and exhaustion will work as well.

As for running tests, you see how hard, expensive and time consuming testing films and fixers are. Literally millions were spent at Kodak to come up with these formulations with all the tests mentioned above and more. You see, everything mentioned here plust image stability and image structure were tested with exact quantitative measurments to determine the results. Somtimes it took years to get approval for a new fixer with the results being peer reviewed in-house before release. And, it was done by two groups to avoid bias. The originating engineer had to run these experiments, and then they had to be duplicated by an impartial engineer in another group. Then the results were compared in a peer review.

That is why I accept prepackaged chemistry. It takes the burden off my shoulders. If I do make a new mix, I test it before I use it.

But, an interesting observation has grabbed my attention. All of the 'staining' processes are doing is creat a pseudo dye in the coating around the silver grain. This dye blurs the grain, but can also detract from sharpness. But, my point is this, or rather my question is this. What is the stability of this pseudo dye? What will happen to 'stained' negatives over time. Does the pyro induced coloration fade? It certainly fades or is bleached in acid sulfite fixes. Is it not fair to assume that the stain/tint/dye is less stable than the silver and will change over time?

I just wonder if anyone has run that type of test. Because, if the dye is not stable, then all of this discussion about staining developers is moot.

PE

Pyro is one of the oldest developing agents. There should be some negatives remaining from those days. My grandfather's glass plate negatives made before 1905 could have been done in pyro or MQ, I don't know which. A few show signs of incomplete washing. A problem is that the pyro stain was not wanted by most, and enough sulfite was used to prevent most of the staining. The standard developer at the time of Hardy & Perrin's Principles of Optics, 1932, contained 70 grams sodium sulfite, 17 grams sodium bisulfite, 20 grams pyrogallic acid, to make a liter of solution A and 75 grams sodium carbonate, 1 gram potassium bromide to make 1 liter of solution B. Equal parts of A and B were used for the working solution. I doubt there is much stain when one develops in that solution. Hardy & Perrin state that the color coefficient of a pyro developer depends on the amount of restrainer and do not mention sulfite. The color coefficient is the ratio of gamma measured photographically to that measured visually, and ranges from about 1.3 with the usual amount of restrainer to as much as 3 with no restrainer. We might get some idea of stain fading from any negative known to have been developed in pyro simply by printing it on graded paper and VC paper, but it would be a very rough idea.

It's interesting that pyro was the sole developing agent.

Gainer, one of my old books states that "an acid stop bath should be used to remove the unsightly stain from the pyrogallol".

Another popular developer around the (previous) turn of the century was the iron sulfate developer, which gave bluish-black tones to the negative.

The worst that could happen is uneven fading. If the dye faded evenly , it could be restored by bleaching and redeveloping in a staining developer.

[QUOTES=BobNewYork;568267]
"The Darkroom Cookbook and/or The Film Developing
Cookbook indicate that sodium thio. may not adequately
fix modern emulsions so ammonium thio is the way to go."

Sodium thiosulfate is the fixer. The ammonium is the
speed; Rapid. Given some more time over the rapid
the slower sodium form will thoroughly fix.

"Also, over-fixing in sodium thio will start to bleach
the image - ammonium doesn't have these problems."

Just the opposite of at least the conventional wisdom.
I wonder though which has the most potential to bleach,
an acid or alkaline fixer?

"The value of short wash times without the additional HCA
bath cannot be over-estimated either!"

Little time spent washing is in my mind to be preferred
to short wash times. Dan

dancqu said:

[QUOTES=BobNewYork;568267]
"The Darkroom Cookbook and/or The Film Developing
Cookbook indicate that sodium thio. may not adequately
fix modern emulsions so ammonium thio is the way to go."

Sodium thiosulfate is the fixer. The ammonium is the
speed; Rapid. Given some more time over the rapid
the slower sodium form will thoroughly fix.

"Also, over-fixing in sodium thio will start to bleach
the image - ammonium doesn't have these problems."

Just the opposite of at least the conventional wisdom.
I wonder though which has the most potential to bleach,
an acid or alkaline fixer?

"The value of short wash times without the additional HCA
bath cannot be over-estimated either!"

Little time spent washing is in my mind to be preferred
to short wash times. Dan

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I'm confusing about Sodium Thio and Ammonium Thio also the Alkaline and Acid Fixer. I can't find the Ammonium Thio in Thailand so I use the TF2 (alkaline fixer) which is based on Sodium Thio. Is it ok to wash the Pyrocat?

There is some doubt whether modern film emulsions (meaning T-grain and Delta) will be fully fixed with a sodium thiosulfate fixer since these emulsions contain more silver iodide than most "older" emulsions. silver iodide is a lot more difficult to dissolve than either silver bromide or silver chloride, the two other components in the silver halide crystals in the emulsion.

The ammonium in ammonium thiosulfate has an accelerating effect on the dissolution of silver halides, as the ammonium ions also form soluble silver complexes.

So it doesn't matter which developer you use, only which film you use.

If you want / feel you need the extra "zap" of ammonium thiosulfate, you can add ammonium chloride to the fixer. Or for that matter - look up "OF-1" in the recipe section here. That's an alkaline rapid fix based on sodium thiosulfate and ammonium chloride.

Thanks Ole, I'll try the OF-1. Can it fix the FB paper?

TN98 said:

Thanks Ole, I'll try the OF-1. Can it fix the FB paper?

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So far, it has fixed everything i've tried. There's nothing "magic" about it, just a little applied chemistry.

It works. It fixes film and paper, even T-max and Bergger Art Contact (both contain silver iodide, AFAIK).

It can be used full strength or diluted 1+1, although I prefer full strength and would only recommend full strength for film.

Ole said:

There is some doubt whether modern film emulsions
(meaning T-grain and Delta) will be fully fixed with a
sodium thiosulfate fixer since these emulsions contain
more silver iodide than most "older" emulsions. silver
iodide is a lot more difficult to dissolve than either
silver bromide or silver chloride, the two other
components in the silver halide crystals
in the emulsion.

The ammonium in ammonium thiosulfate has an
accelerating effect on the dissolution of silver halides,
as the ammonium ions also form soluble silver complexes.

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The thiosulfate ion is one of only two ions which will dissolve
ANY salt of silver. The ammonium ion will complex with silver
where many of the not so very insoluble salts are involved.
The ammonium ions affinity for silver in the presence of
iodide is near nill.

Verification of the above are the much longer fix times
and much reduced capacities of Rapid fixer when iodide
is present. Thiosulfate carries the load due to it's much
greater affinity for silver. Where iodide is not involved
an ammonium fixer can be RAPID. Dan

PE,

I quote Richard Knoppow on this (perhaps you know him, he seems quite knowledgeable, but I do not know his source, I could ask.):

"The stain however, is not a dye, but rather, a pigment
related to Humic Acid, the substance which colors wood
brown. Unlike dye it is very permanent, more so than the
silver."


Best,

Cor

Photo Engineer said:

But, an interesting observation has grabbed my attention. All of the 'staining' processes are doing is creat a pseudo dye in the coating around the silver grain. This dye blurs the grain, but can also detract from sharpness. But, my point is this, or rather my question is this. What is the stability of this pseudo dye? What will happen to 'stained' negatives over time. Does the pyro induced coloration fade? It certainly fades or is bleached in acid sulfite fixes. Is it not fair to assume that the stain/tint/dye is less stable than the silver and will change over time?

I just wonder if anyone has run that type of test. Because, if the dye is not stable, then all of this discussion about staining developers is moot.

PE

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I have found both good and bad information in the work of Knoppow, just as you will find errors in mine.

Humic acid is not a 'classic' pigment. Cadmium yellow and red lead are pigments, etc. etc. Humic Acid is what I would term a dye. And, this gets back to my basic question. All dyes fade with time, but most pigments do not. Therefore the humic acid dye may fade. Since no one has done a stability test on it, IDK what the answer is.

PE

Both Ammonium Thiosulfate and Sodium Thiosulfate fix silver halide, and both will bleach a silver image if the film or paper is left in the solution long enough. They will both bleach on the acid or alkaline side, but on the acid side the bleach reaction is much faster.

PE

gainer said:

If the dye faded evenly, ...
it could be restored ... in a
staining developer.

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Dye then Stain. How about Tan? Tanned gelatin
of one hue or another. Tanning developers. There
is no stain or dye involved. A fine point perhaps
but removes the ambiguity. Dan

dancqu said:

Dye then Stain. How about Tan? Tanned gelatin
of one hue or another. Tanning developers. There
is no stain or dye involved. A fine point perhaps
but removes the ambiguity. Dan

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Tanning developers typically produce colored image stain that is proportional in density to the amount of exposure received. So, you end up with a silver image, a stain image and tanned (hardened) gelatin in the exposed areas of the emulsion. Stain and/or dye may both be involved, depending on the emusion design.

See Haist vol. 1, pages 519-521.

Pyrogallol and Catechol based developers can provide good examples of staining and tanning phenomena with many different emusions.

Tom Hoskinson said:

Tanning developers typically produce colored image stain ...

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Redundant. Similar to 'from whence' when 'whence' says it
all. Not exactly Redundant as the gelatine when tanned
has a color. No dye or stain needed. At least that's my
understanding. I suppose the color of the gelatine
varies according to the tanning agent and
conditions under which it is used. Dan

dancqu said:

Redundant. Similar to 'from whence' when 'whence' says it
all. Not exactly Redundant as the gelatine when tanned
has a color. No dye or stain needed. At least that's my
understanding. I suppose the color of the gelatine
varies according to the tanning agent and
conditions under which it is used. Dan

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Not redundant - there can be several different things going on. Tanned gelatin may or may not have color, tanning does produce a persistant hardened gelatin relief image. Bleaching the film and redeveloping it can provide a lot of insight.

The following is an example of redundancy: See Grant Haist, Vol. 1, pages 507 thru 521.

Matrix film developer contains pyrogallol. So, it is possible to get both staining and tanning take place at the same time. In fact, the tanning effect could be used to improve sharpness by having imagewise swell effects change the surface of the film much as is seen in Kodachrome.

PE

PE has an interesting idea there. I have seen some old negatives that had that relief effect with the pyro stain. As far as I know, matrix film developer was Kodak D-175 or something similar:

Kodak D-175 Tanning Developer

Solution A

Pyrogallol 4 g
Sodium sulfite, anh. 5 g
WTM 1 l

Solution B

Sodium carbonate, anh. 25 g
WTM 1 l

Mix A and B just before use. Develop 5 to 8 minutes.

Notice that this has a fair amount of sulfite (2.5 g/l). Stain and tanning are at least somewhat independent. But the old dye transfer books warn you about the limited life of mixed matrix film developer.

The reasons given in most texts for using an acid fixer are to finish the work of the stop bath to ensure the development is ended predictably and to prevent stains. It really does help prevent those curious and unpleasant splotches that happen when the careless worker carries developer over into the fixer. But it may inhibit some of the staining from pyro developers. I haven't seen any good quantitative work on that subject. My favorite fixer is Kodak F-34, and old color formula that works just fine with black and white film and paper. It's barely acid (pH 6.5). I've used it with Pyrocat HD, and I haven't noticed any effect on the stain, but Pyrocat has relatively light staining in any case. I use fixer as a one-shot for film, and I dump the print fixer after one or two sessions, so life and contamination are not big issues for me.

I've used staining devs for the last 13 years, usually fixed in Hypam/IRF-seems to have no visible effect on the amount of stain present [an alkaline fix doersn't seem to make any visible difference IME].So I'm sticking with Ilford/Fotospeed for film as they're readily available , though I might use an alkali fix with FB paper.

"Modern photographic emulsions designed for tanning development may contain one other compound: the tanning agent itself."

Grant Haist, Modern Photographic
Processing, Vol 1, page 520.