Formulating a sharp solvent MQ developer

[Gerald C Koch]

There are many sulfur containing organic chemicals that can be used as silver halide solvents. However, most are not practical to use. There are many problems associated with them. Some are toxic or cause skin and eye irritation. Many are expensive or hard to obtain. Others are very odoriferous and many are untested as for carcinogenic activity. For example, the military used thiophenol as an ingredient in their vomit gas since the smell causes spontaneous vomiting. Of the compounds that Haist mentions it is interesting to note that he uses only sodium thiosulfate in his monobath MM-1. Kodak used 2-thiobarbituric acid in their BW reversal kit. I should note that unsubstituted barbituric acid (and also the thio compound) have no sedative effect so that they are not drugs.

It should be mentioned again that unless you have some chemical training you really should avoid these compounds.

[Alan Johnson]

Again, my aim is not to achieve a particular high degree of sharpness, but to get the best sharpness possible using a classical MQ developer (or MAscorb.).

More from Crawley BJP Dec 16 1960:
"It is possible to adapt standard MQ borax (Crawley's name for D-76)to give better sharpness and definition, and this has been done in the...Adox standard MQ borax formula....
metol.............................1g
sodium sulphite anh..........80g
hydroquinone...................4g
borax.............................4g
potassium bromide............0.5g
water to.........................1L
The concentration of sodium sulphite is 20 grammes lower than in D-76,which reduces the amount of physical development and improves sharpness.The sheen referred to earlier in D-76 appears to be caused by the nature of borate alkalinity(in a sensitive carbonate chemical developer the introduction of borax in a concentration of 0.1 grammes per litre will produce a slight sheen).The addition of potassium bromide to a borax developer suitably re-balanced will remove this sheen virtually entirely,and improve definition, for it appears to prevent discontinuities usually caused by borax alkalinity.The buffering of borax with added boric acid does not seem to improve definition,although the borax sheen is reduced and sharpness improved "
"A futher step away from the parent D-76 is...FX-3.."

So Crawley attributed the improvement of sharpness with the Adox developer largely to the reduction in sulfite ,as well as reduction of sheen.His arguement about the added boric acid presumeably refers to the doubling of the borax content from 2g/L in D-76 to 4g/L in the Adox version.

[Gerald C Koch]

More from Crawley BJP Dec 16 1960:
"So Crawley attributed the improvement of sharpness with the Adox developer largely to the reduction in sulfite ,as well as reduction of sheen.His arguement about the added boric acid presumeably refers to the doubling of the borax content from 2g/L in D-76 to 4g/L in the Adox version.

I wonder on what Crawley based this conclusion since the Adox formula has only a passing resemblence to D-76. The amounts of the chemicals are all different. Did he perform tests varying only one chemical at a time? Sadly there is much written on developers that is not based on the scientific method.

[Ian Grant]

I wonder on what Crawley based this conclusion since the Adox formula has only a passing resemblence to D-76. The amounts of the chemicals are all different. Did he perform tests varying only one chemical at a time? Sadly there is much written on developers that is not based on the scientific method.

There's a misprint in the Adox Borax MQ formula in the 1960 article which is given in the text rather than written out as a Formula. It should be 2 gm Metol.

Kodak didn't intended D76 to be a still camera developer it was designed to be motion picture developer. They then spentover 15 years trying to improve it.

Crawley's conclusions are based partly on the results of using the Adox Borax MQ developer because it does give finer grain, better sharpness, excellent tones and an increase in effective film speed compared to D76. It's related to Agfa 44 and Agfa ansco/GAF 17. We used this developer commercially in the 80's in deep tanks at work and I suppled it to another photographer for a few years for his deepn tanks.

Intertestingly Ilford dropped the Sulphite level in ID-68/Microphen to give better film speed, it gives better sharpness but more defined grain.

Ian

[Alan Johnson]

I wonder on what Crawley based this conclusion since the Adox formula has only a passing resemblence to D-76. The amounts of the chemicals are all different. Did he perform tests varying only one chemical at a time? Sadly there is much written on developers that is not based on the scientific method.

It would seem likely that in 1960 it would have been known that decreasing sulfite increases sharpness since by then D-76 was in use for over 30 years.So Crawley would not have had to prove it.
However it is not mentioned in 1960 BJP Almanac or any other pre-1960 books I have that decreasing sulfite increases sharpness.

[Gerald C Koch]

It would seem likely that in 1960 it would have been known that decreasing sulfite increases sharpness since by then D-76 was in use for over 30 years.So Crawley would not have had to prove it.
However it is not mentioned in 1960 BJP Almanac or any other pre-1960 books I have that decreasing sulfite increases sharpness.

As I have mentioned before decreasing the sulfite content of D-76 from 100 g/l will cause a loss in sharpness until the concentration falls below ~70 g/l. As you say there seems to be no mention in text books on the ideal sulfite concentration. The amount of sodium sulfite (100 g/l in D-76 and D-23, ...) seems to be based on "if a little is good then more is better." What was known empirically in 1960 was that D-76 1+1 produced greater sharpness. But remember that when diluted all the chemical concentrations are halved. So claiming that the increase in sharpness is due to decreased sulfite concentration is a perfect example of a post hoc ergo propter hoc falllacy.

[Ryuji]

There are many problems associated with them. Some are toxic or cause skin and eye irritation. Many are expensive or hard to obtain. Others are very odoriferous and many are untested as for carcinogenic activity.

Same applies to a lot of toners, but when there is no better alternative, it ultimately is up to a responsible judgment by each artist.

I generally prefer to use safe and non-wasteful option whenever possible, but I don't hesitate to use sulfur toners and selenium toners with appropriate precautions.

Again, my position on this thread is that there is better approach in Phenidone-ascorbate formulation so I'm not too crazy about it. But if one is serious about the goal of this thread, it is important to understand how these additives work, at least in the theoretical framework.

[Ryuji]

That's interesting ! Do you know published formulas using mercaptoisobutyric acid or 3-mercaptopropionic acid ? (by the way, these acids are forbidden in Europe).

Could you develop ?

Again, my aim is not to achieve a particular high degree of sharpness, but to get the best sharpness possible using a classical MQ developer (or MAscorb.).

Check out the paper by Haist and Pupo published in Photographic Science and Engineering, Vol 20, Number 5, pages 220 to 224, 1976. Good amount of data and discussion there.

For the development inhibiting coupler, there are a couple of US patents, but the approaches disclosed therein are not very easy to prepare in amateur darkrooms (nor do I think it is necessary). Again, it is an interesting approach worthwhile studying.

[Ryuji]

Ryuji, what about anti-silvering agents? Could that be an avenue to pursue when trying to formulate sharper (perhaps only slightly sharper, but still...) solvent developers? I believe Microdol-X contained a weak anti-silvering agent (not that one would have ever used Microdol for sharpness unless it was highly diluted). And Ilford ID-11 Plus reportedly contained an anti-silvering agent as well, although it was apparently in there for anti-sludging purposes.

I do use a form of mild anti silver agent in my developer, but the efficacy of this compound varies a lot depending on the film. It works very well on Plus-X but not so much on Delta 400, for example. It doesn't hurt image quality regardless of the film, and it is a very safe compound and I have enough stock of it, so I leave it in my formula. But you can't buy it from photographic supply houses. These agents may be effective in preventing dichroic fog and some general fog, and in some cases I feel the grain distribution to become a bit more even (rather than mottled) but there is no magic there.