This probably is the best explanation. If true it suggests that there may be room for optimising a developer for a specific film.
If you look into other creations of the German company SPUR, offered through Rollei and Adox, they are based on a principle that IMHO transcends the Cookbook II universe. Also, Bob Schwalberg would likely have labeled them as an abomination. In my understanding, the concept behind these developers is to achieve a certain characteristic curve for a limited number of films, in most cases for just one film. This is achieved by balancing the development speed of several superadidtive phenidone/hydroquinone or phenidone/HQMS combinations with silver halide solvent action. Without thiocyanate these developers are excessively active, even if used diluted 1:10, and produce rather prominent grain. The entire idea of one film/one developer is alien to what was typically offered in the 20th century. Also, by definition, they are one shot formulations. Disclaimer: no affiliation with SPUR.
Sorry for the confusion. In post #9 you were speculating about why 5 developers were used, and I offered the quote from the book as one possible reason - that is, there may be some regulatory advantage. I do agree that if both a scientific and a more common name were given, it would be most helpful.It wasn't me who said this, but I think using more than one ingredient to perform a function can make a list look better. For example, if the list of ingredients on a shampoo bottle have to be listed in declining order of quantity, something can be made less obvious if its percentage is reduced by another similar ingredient. I can't think of a specific example at the moment but I have observed it.
Also, instead of saying Metol or Dimezone-S or glycol a much more complicated (correct) but less recognized name can be used.
If you look into other creations of the German company SPUR, offered through Rollei and Adox, they are based on a principle that IMHO transcends the Cookbook II universe. Also, Bob Schwalberg would likely have labeled them as an abomination. In my understanding, the concept behind these developers is to achieve a certain characteristic curve for a limited number of films, in most cases for just one film. This is achieved by balancing the development speed of several superadidtive phenidone/hydroquinone or phenidone/HQMS combinations with silver halide solvent action. Without thiocyanate these developers are excessively active, even if used diluted 1:10, and produce rather prominent grain. The entire idea of one film/one developer is alien to what was typically offered in the 20th century. Also, by definition, they are one shot formulations. Disclaimer: no affiliation with SPUR.
For the actual type of developer, I'd say from what I've heard and seen about it, it's a non-solvent developer EXCLUDING the thiocyanate, but a mildly solvent developer with it, and of unknown speed. That just requires measurement. Non-solvent can be speed reducing (can't develop the "deeper" grains) or maintaining, while solvent developers can be speed reducing (eats away subtle shadows), speed maintaining, or speed increasing (can develop "deeper" grains than a standard developer otherwise could). Developers with thiocyanate are typically very mildly speed increasing, while developers with chloride are typically speed reducing because chloride only is solvent to exposed grains and so in an unbalanced developer could eat at subtle shadows before it has a chance to develop. The total developing agents are:
* Phenidone/Dimezone (these are likely combined due to manufacturing and not specifically by design. ie, they can use lower grade product by compensating for a mixture. Either way they work very similar to each other)
* metol/derivative
* HQMS -- Likely used here solely to regenerate the M and P parts consistently without letting contrast run away and for longer shelf life (HQMS is more stable than HQ and more can be added than HQ to ensure the P and M stays alive). HQMS of sufficient purity is very difficult to source in small amounts today so it is rarely used by hobbyists
* HQ -- used to increase contrast and highlight development most likely
The thiocyanate is a real wild card here as it's a very rarely used component these days because of various problems. Some films can have dichroic fogging with it, and it can often be too solvent or in the wrong ways, and definitely will increase highlight density.
edit: one important detail about thiocyanate that's not often appreciated because of it's strange behavior is that it actually can act as a restrainer against HQ specifically. There's not much research on this other than a single paper from the 70s, but I've confirmed it myself in lith developers. It's weaker than bromide but stronger than chloride in this respect. It highly depends on formulation as to if it behaves more as a restrainer or an accelerator.
edit2: according to the CAS number, it is metol and not a derivative. Strange way they named the chemical though
Thank so much for this, and also your additional information in post #17!
I am curious about 'fogging develpers' as mentioned in post #17. Unfortunately, the FDCB has a very thin Index and even slimmer glossary with no entry for fogging. After a very brief search, am I wrong to conclude that "fogging developers" are only considered to be a good thing in reversal processes?
I consider Agfa Agfapan APX to be the fastest ISO 100 film. Now sadly long gone. YMMV, of course.Back in the APX100 days, I remember the fotoimport.no site claiming that it didn't reach ISO100 in Xtol, it was ISO64/50 or thereabouts. This is quite strange, considering that Xtol gives full film speed. So, this may indeed be a developer custom formulated to five the best possible speed/curve shape.
I had never tried the APX100 - Xtol combination at box speed with in date film. Some 10 years out of date film I tried rather recently definitely wasn't capable of reaching box speed in Xtol, but was also surprisingly foggy.I consider Agfa Agfapan APX to be the fastest ISO 100 film. Now sadly long gone. YMMV, of course.
I used Rodinal and Ilfotec HC in my case.I had never tried the APX100 - Xtol combination at box speed with in date film. Some 10 years out of date film I tried rather recently definitely wasn't capable of reaching box speed in Xtol, but was also surprisingly foggy.
@earlz I really like how you bit down hard into lith developers and learned a lot about developer chemistry in general. Very nice to see. Keep it up.
Yes, Rodinal worked ok, Agfa even suggested EIs of 125/160 in Rodinal 1+25 and 1+50 respectively IIRC. Not the finest grain, but looked nice overall.I used Rodinal and Ilfotec HC in my case.
Well, not only ok, but superb would be the word I'd use, based on darkroom prints, not scans. Very fine grain, nice tonality, a perfect match if I may...Yes, Rodinal worked ok, Agfa even suggested EIs of 125/160 in Rodinal 1+25 and 1+50 respectively IIRC. Not the finest grain, but looked nice overall.
Agfa's recommendations for development gave fairly high contrast, too much for me even with a diffusion enlarger. I concluded that their recommendation was to justify the speed rating. I exposed more and developed less and I was happy with the result.Yes, Rodinal worked ok, Agfa even suggested EIs of 125/160 in Rodinal 1+25 and 1+50 respectively IIRC. Not the finest grain, but looked nice overall.
I used to print with a condenser enlarger and the development recommendation was a bit on the high side, but still manageable. I cut back on development time and used the 1+50 dilution, which gave better results, while using box speed. While my film was reasonably fresh, I also used stock homebrew Perceptol at EI 50. Obviously, I lost some acutance, but the results were simply beautiful.Agfa's recommendations for development gave fairly high contrast, too much for me even with a diffusion enlarger. I concluded that their recommendation was to justify the speed rating. I exposed more and developed less and I was happy with the result.
I had never tried the APX100 - Xtol combination at box speed with in date film. Some 10 years out of date film I tried rather recently definitely wasn't capable of reaching box speed in Xtol, but was also surprisingly foggy.
Reputedly it’s coated from at least some leftover chemistry from the original Scala that was left when Leverkusen shut down. The current stock is probably all there will ever be in the current incarnation. Mirko says if they bring it back it will require someone else’s sensitizers because Silvermax/Adox Scala used Agfa’s.Adox got all the old Agfa patents and formulas IIRC. Could Silvermax be a reincarnation of an older Agfa one?
Funny that you mention Bob Schwalberg. On the same page in the FDCB which discusses HQMS, Schwalberg is quoted as saying,
"One developing agent is best, two is okay, three is very suspect, and four the guy is definitely a jerk."
Thanks for your insight about the possible mechanics of the developer. As someone who is still trying to learn the language needed to understand these developer discussions, can I ask for a clarification about 'active' developers? I assume more active developers are faster (have shorter development times), but is there more to it than that? Does knowing a developer is 'active' allow me to predict some directly related effect that can be seen on the developed negative?
In <this technical bulletin> ADOX do say "SILVERMAX developer has ben especially formulated for the SILVERMAX film." But also, "SILVERMAX can be used as a very good equalizing developer for any other film as well. In order to tweak it for other manufacturer ́s films you need to adjust the dilution as given on the table on the next page." (They go on to warn the user not to expect the same "14-zone" range they promise for Silvermax film if developing other films.)
The table shows times, temps, and dilutions for a dozen other films from five other companies. As for dilutions, ADOX gives specific dilutions for each of the dozen films which range from a low of 1+17 for Ilford Delta 400 to a high of 1+30 for Ilford Dellta 100 and Fuji Acros 100.
Thiocyanate is a good accelerator, if used in moderate amounts. It may be a restrainer in very small amounts, since AgSCN is very insoluble. Only the higher complexes Ag(SCN)x are soluble, but they will only form, if enough thiocyanate is present. PE once suggested, that the combination of strong solvent and restrainer increases sharpness. This may well be another reason, why E6 FD contains both. Kodak was obsessed with sharpness, as were their customers.The thiocyanate is a real wild card here as it's a very rarely used component these days because of various problems. Some films can have dichroic fogging with it, and it can often be too solvent or in the wrong ways, and definitely will increase highlight density.
There are really only two weird things with this developer as I see it:
2: The addition of a very small amount of metol. Its function is also unclear to me as it's unlikely to contribute significantly to the development in the presence of a larger amount of vastly more active phenidone/dimezone.
PS: I recommend everyone look at E-6 FD formula to see that latest&greatest of Kodak's B&W developers. They had the budget to optimize this thing long after their B&W research was shut down.
Have you tried it?US patent #4366234 by British chemists Wheatcroft and Wall of 1981 described a way producing hydroquinone monosulfonate by treating hydroquinone with peroxide in the presence of excess sulfite. The entire mixture is then added to a first developer for color reversal (which, unfortunately, contains mistakes in the patent). This is an easy way to get your hands on HQMS, which is quite hard to get as powder.
I really doubt that it works as it claims. Try adding some peroxide to a sulfite solution and watch the temperature. It reacts instantly with sulfite and I seriously doubt that it has much an effect on hydroquinone. Hydroquinone will oxidise with peroxide to give quinone, but ideally needs some iodide as a catalyst. Quinone will react with sulfite to give a hydroquinone monosulfonate salt, but also requires specific conditions. This patent seems too good to be true and at least one forum user who tried it didn't get very good results. Rather iffy IMHO.I did, in a limited way. My interest was not in the 1st developer for color reversal, but a soft phenidone developer, like Rollei RLC. All I can say that the resultant solution does not develop like hydroquinone does, in conjunction with phenidone it does give a soft developer, and the "HQMS cocktail" is reasonably stable after it was made, otherwise this test is still ongoing.
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