Doremus, thank you for your kind observations, I appreciate them. I don't find that compounding my own developer, or fixer, takes much time at all. As ammonium thiosulfate is a liquid, I find it is, actually, a very fast procedure. Further, it is not taking an awful lot of my time and effort. I do it, because I do enjoy this part of photography, albeit not as much as the creative part. Besides, I have a strong scientific background and I have always liked to question things till I understood them. I fully appreciate your points about Haist and others having done this work professionally, but it has been a while since things have progressed, since those days. I am sure there are improvements that can be made, and if no one asks questions, not much is likely to happen. Even because of Ryuji's, and Mark Overton's work, we have those new options, that did not exist a few years ago.
So, even if it did not apply to my practical desire to improve my existing process, which is very similar to yours, I would still like to understand the impact of sodium sulfite on archival/optimum fixer capacity, or of ammonium thiosulfate in KRST on the same, and about good buffers for a neutral fixer, so as to be even better to the process, results, and the environment. Besides, I find photochemistry, just like the tone reproduction process, truly fascinating, and I yearn to understand the logic behind them, as much as I am able to.
I've been looking for information on that for a while and came up empty. Fact is that the Selenium in selenium toner is so toxic that few home brewers are willing to mix this toner from raw chemicals - at least I definitely wouldn't. Therefore I don't think we will see much published data on that.
Originally Posted by Doremus Scudder
Among the later books on photo chemistry are Haist's two volumes, and these books don't even mention Ammonium Thiosulfate. Why? Because Kodak would have stomped on Haist's feet if he would published trade secrets! What does this tell me? There isn't much published about modern fixers, at least not with solid data and reproducible results, and even patents are mostly vague or intentionally misleading. Most published data (formulas and test results, not instruction manuals) on fixers is simply not applicable to modern products.
Originally Posted by Doremus Scudder
Testing, at least at amateur level, is much easier for fixers than for developers. Measuring speed and grain (as Mark Overton did) requires some apparatus, and measuring sharpness (reliably!) is beyond reach for most of us. Measuring clearing speed is trivial, and tests for residual silver and hypo are cheap and available, with published recipes. The biggest obstacles to fixer improvements at the amateur level are the cheap availability of commercial rapid fixer (most of the time these commercial soups cost half or less of what the raw chems would cost us!) and the fact that fixers don't visibly improve your prints (for the first 10 years at least).
Is there a motivation for home brewing or testing fixers? Apparently TF-5 fixer runs circles around standard commercial rapid fixers, especially in terms of working solution life, but it's economically unfeasible to ship it across continents and its recipe is unpublished. A version of Farmer's reducer would be nice that has a working solution life of 8 hours (one really long dark room session). Likewise there is little to no data available for alkaline fixers, or even just simple data points like "what's the most economical way of archival fixing for TMX/TMY that leaves no magenta stain?" or "how can I translate a fixer's clearing time of film X into archival fixing time of paper Y?".
Rudi, I couldn't agree more. I feel that I will have to do a fair amount of testing for the residuals, and just keep a score of what goes through my fixer attempts. Ammonium thiosulfate 60% is not cheap, but it works out the same price (or marginally cheaper) as the ready-made standard, acidic product from Ilford, and much cheaper than the specialised fixers from smaller retailers. However, it is not the price that drives me to do this. Having said that, if I had access to TF-5 at a price similar to what our US friends pay, I probably would not be formulating something of my own.
Still, I would be researching, and perhaps testing, with regards to the function of sodium sulfite wash-aid on fixer capacities, and I'd love to know if ammonium thiosulfate in KRST helps, but I guess I am repeating myself. I agree with you how curious it is how little there is to be found on those interesting points, which clearly have an impact—or Ilford and others wouldn't have mentioned it.
Curiously while selenium is poisonous it is also a necessary trace mineral in the body. As Pasteur said it is not the poison but the dose. Here are some of the symptoms that can result from this type of deficiency: cardiovascular disease, nerve degeneration, hypothyroidism, arthritis, anemia and a dry, scaly scalp. A selenium deficiency may even increase the chances of developing some forms of cancer.
As with many chemicals selenium can be handled safely with proper care. Avoid breathing the powder or skin contact with the element or its solutions. So for the day when commercial preparations are no longer available here is one formula for a selenium toner.
Kodak T-55 Selenium Toner
This formula is similar to Kodak Rapid Selenium Toner.
Distilled water (50°C) …………………………………………… 750 ml
Sodium sulfite (anhy) ……………………………………………… 150 g
Selenium metal, powdered† …………………………………… 6.0 g
Ammonium chloride ………………………………………………………… 190 g
Distilled water to make ………………………………………… 1.0 l
†Exercise care when handling this chemical.
Method of Preparation
With adequate ventilation:
Dissolve the sodium sulfite in the indicated amount of water, then add the
selenium and boil the mixture for 30 minutes. Allow the solution to cool and
filter any remaining residue. Dissolve the ammonium chloride in the solution
and make up to 1 liter with water.
For use dilute the stock solution 1+5 to 1+9. Immerse the print for 10 to 15
minutes until the desired tone is achieved and then wash and dry the print.
The diluted solution does not keep.
B.L. Twinn, "Some Enlarging Papers and Developers for Miniature Work",
Photo J. 78: 483
Thanks for posting that formula, but can you tell me why this one uses no Thiosulfate while Kodak's KRST lists copious amounts of Ammonium Thiosulfate in their MSDS? All this suggests that Thiosulfate improves the real KRST somehow.
And a quick afterword on Selenium toxicity: its LD50 seems to be quite high (>6g per kg body weight), but it seems to cause bad things when we are exposed to much much lower levels every day.
Haist does talk about Ammonium Thiosulfate, and includes several formulas. I would say it isn't really modern and/or rapid fixers that aren't discussed in publications, rather modern alkaline and/or non hardening rapid fixers that aren't discussed. The fixers in Haist, whether Sodium or Ammonium based, are mostly hardening fixers, which normally require acidity.
Originally Posted by Rudeofus
I have no idea why ammonium thiosulfate is in KRST. There is another toner mentioned by Ansel Adams which contains sodium sulfide, selenium, and sodium thiosulfate which produces brown tones. The re-development type seleniun toners do not contain thiosulfate for obvious reasons.
Sodium seleno-sulphate is analogous to sodium thiosulphate with selenium replacing one sulphur atom. This is something I copied from the web years ago, posted by someone called Liam. I'm sorry I can't make a more complete attribution. The thiosulphate apparently accelerates the toning, and makes the toner more stable.
Originally Posted by Gerald C Koch
<start of quote>
a bit of info from Clerc:
The use of selenium in the form of seleno-sulphate* (with ammonium chloride
added) for toning print-out papers was suggested in 1912 by P. Rehlander as
being more economical than toning with gold and platinum. [Clerc says
elsewhere that the same solution is fine for development papers.] Even with
papers that have been well washed to remove the soluble silver salts, toning
with sodium selenosulphate tends to stain the whites of the image very
strongly. This trouble can be obviated, when toning is done after fixing
and washing, by adding a small quantity of sodium hyposulphite [what they
then called sod. thiosulphate, or hypo] to the toning solution (Lumiere and
Seyewetz, 1924). This procedure greatly increases the speed of toning. The
tones obtained vary from dark brown to red**, according as the image is
coarse or fine grained; this toning gives (with certain papers) an
appearance of platinum toning when used on a print which has been toned with
gold and fixed.
Sodium selenosulphate may be obtained by dissolving 260 gr. of powdered
selenium in 20 oz. (30 grm. in 1,000 c.c.) of a warm 20 per cent solution of
anhydrous sodium sulphite.
Twenty to 50 minims of this solution are added to 20 oz. of a 30 per cent
solution of hypo (2 to 5 c.c. per litre of hypo solution). The smaller
quantity is used for toning albumen papers and the larger for emulsion
papers (gelatine or collodion P.O.P.). The bath is limpid, colourless, and
Toning is very rapid, taking from 2 to 5 minutes, according to the degree of
exhaustion of the bath. This toning solution is very economical; 35 oz.
(1,000 c.c.) will tone 80 prints 7 X 5 in. in size, and the results are
highly permanent if washing is properly done.
* Selenium, which in many of its properties resembles sulphur, appears
usually as grey crystalline masses; in a fine state of subdivision it is
generally red. The alkaline selenosulphates, and particularly the sodium
salt (Na2SSeO3), have a constitution which is closely analogous to that of
the hyposulphites (Na2S2O3), the selenium replacing a portion of the
sulphur. Just as thiosulphate is obtained by dissolving sulphur in a hot
solution of sulphite, so selenosulphate is obtained by dissolving selenium
in hot sulphite solution. As selenosulphate is not made commercially it
must be prepared as required by dissolving selenium. Solutions of
selenosulphates should be kept in full bottles, well stoppered to avoid
conversion into inactive selenotrithionates by oxidation; they are more
stable in presence of sodium sulphite or hyposulphites. Analogous compounds
of tellurium have also been used for the toning of silver prints.
Everyone, thanks for your contributions to my question, very much. I think it would be helpful—at least to me—to split the discussion off into two more threads, one dealing with sodium sulfite and the other about ammonium thiosulfate in KRST. This way, I would hope, we might get more contributions, now and in the future, as the current title of this thread is no longer applicable to those two trains of thought. New threads being posted in a minute or so.