So, Gerald, would you agree that in the Germain metol-PPD-glycin 777 combination only metol would work as developing agent, and the other two will develop only weakly if at all?PPD is a very weak developing agernt almost always used for its solvent nature to silver halide. Glycin is a slow but powerful developing agent. To increase its speed it benefits from a higher pH. Orthophenylenediamine has NO developing characteristics and is used a as solvent alone.
PPD has a distinctive odor that is usually described as pleasant or as medicinal ie the smell of an old time drugstore. Solid Glycin is easily oxidized but once in solution resists oxidation.The prence of PPD in Harveys is given away by its snell. Glycin is colorless while orthophenylenediamine is yellowish brown and PPD is dark purple. The presence of PPD in Harveys is given away by its small
So, Gerald, would you agree that in the Germain metol-PPD-glycin 777 combination only metol would work as developing agent, and the other two will develop only weakly if at all?
Also, PPD imparts distinctive odor and color, and glycin no odor but color, so what odor and color commercial Harvey's 777 has? My Edwal 12 solution now looks like a dilute Ceylon tea.
I guess if anyone really wanted to know what's in Harvey's 777, one would have plunked down real hard cash for a mass spectrometric analysis and been done with it.
I guess if anyone really wanted to know what's in Harvey's 777, one would have plunked down real hard cash for a mass spectrometric analysis and been done with it.
Just to clear up some confusion:
Whatever may be in Harvey's 777, lots of people have already speculated, some even claimed to possess the formula, with neither the speculation nor the claimed formulas having much credibility.
- yes, PPD is slow at pH 8, because its oxidation product still sticks to silver and silver halide and effectively prevents fresh PPD from reaching the grain. Oxidized PPD reacts with sulfite only slowly, which makes PPD only developers slower than Metol+sulfite type developers.
- Yes, Glycin alone is quite a slow developer at pH 8, because it is negatively charged and has only weak tendency to adsorb to silver and silver halide grains. On its own it just doesn't reach the development center quick enough to facilitate quick development action
- No, together they don't perform random miracles, they just work as superadditive combo. PPD does the initial reduction of silver ion to silver, and Glycin happily passes its own electron to oxidized PPD, thereby restoring it to original condition. It's pretty much the same situation as with MQ, PQ or PC type developers.
I guess if anyone really wanted to know what's in Harvey's 777, one would have plunked down real hard cash for a mass spectrometric analysis and been done with it.
LOL exactly .. but that's too easy ..
and it is much fun-er to go by what others imagine it might be
I think that there's probably a good chance one of the CD's has been used to replace the PPD, perhaps compare it to C-41 developer, E6 colour developer, RA-4 developer or Adox Atomal & that might narrow down things somewhat, given that they all use specific (and different) CD variants. They do have distinguishable smells, but describing them is probably harder than experiencing them. Furthermore, I have no great desire to sniff unsubstituted PPD if I can avoid it...
More to the point, I think that Henn et al probably had a pretty good idea of what was going on in 777 (and Edwal 12) & realised that you could probably eliminate everything apart from the metol & sulphite at that pH without significant downsides. If you wanted finer grain still, add a chloride salt (and an antifoggant if needed). KRL would have been deep in work on PPD & its substituted derivatives at the time & I'd be inclined to say that they probably had a clearer idea of their usefulness & effects in the pH ranges in question than either Harvey or Lowe. If they had the claimed effects of E12 or 777, I have little doubt Kodak would have offered an equivalent developer. I'd be interested to see a well controlled comparison between replenished D-23, E12, E10 & 777 (preferably accompanied by photomicrographs & microdensitometric studies), but the difficulty of carrying out the latter essentially puts it out of reach of pretty much anyone outside a manufacturer's R&D lab.
Now that I dug up some literature, I could answer this properly. Lowe's patent US2164280 of 1939 is cited in Henn and Crabtree patent of 1945. The point in the former was that the developer was made up of metol, glycin, sulfite and ammonium chloride, so that the resultant pH was preferably between 7.3 and 7.5. As I mentioned, such developers are extremely slow at 20 degrees Celsius and also that glycin does not really do any developing. An interesting revelation of Lowe is that 10% solution of his sulfite had a pH of 9.7, while currently available reagent grade sulfite would make a solution with pH of 8 to 8.2.That's quite a difference. It means that any current user trying to reproduce Lowe's recipes with high quality reagents would end up with a different developer than the originally intended. Also of note, Henn and Crabtree make a point that their invention is supposed to address the stability of ammonium chloride containing developers, replacing ammonium chloride with a mixture of amine and sodium chloride. Edwals, on the other hand, are clearly coming out of Lowe's work looking for an alternative silver complexing agent in place of ammonium chloride that would also provide better keeping properties. At this point in time, enter the 777.Major problem with assuming that all these developers started as D-23 variants: wasn't D-23 disclosed in 1944 or thereabouts & 777 & Edwal 10/12 came into being in the late 1930's? Edmund Lowe seems to have published the Edwal formulae at least as early as 1939, and articles about 777 date to at least 1938. More importantly, they seem to have started as substitutions on D-76 with glycin for HQ (Edwal 10), then adding PPD ( Edwal 12). Also remember that things like DK-76 & other buffered variants etc of D-76 were disclosed in the later 1930's.
The difference is insignificant, since Sodium Sulfite is an extremely weak buffer at pH 9.7. Once you add Metol, pH will come down towards a range where buffering is strong, i.e. around pH 8.0 - 8.5.An interesting revelation of Lowe is that 10% solution of his sulfite had a pH of 9.7, while currently available reagent grade sulfite would make a solution with pH of 8 to 8.2.That's quite a difference.
The difference is insignificant, since Sodium Sulfite is an extremely weak buffer at pH 9.7. Once you add Metol, pH will come down towards a range where buffering is strong, i.e. around pH 8.0 - 8.5.
Note, that if you mix 100 g/l Sodium Sulfite solution fresh from powder, initial pH will be above 9, and you can observe how pH drops as aerial Carbon Dioxide is dissolved. This happens within the first hour. I would therefore be extremely hesitant to trust any "pH of 10% Sodium Sulfite" number you see. There is some discussion about this here (post 486ff)
The difference is insignificant, since Sodium Sulfite is an extremely weak buffer at pH 9.7. Once you add Metol, pH will come down towards a range where buffering is strong, i.e. around pH 8.0 - 8.5.
Note, that if you mix 100 g/l Sodium Sulfite solution fresh from powder, initial pH will be above 9, and you can observe how pH drops as aerial Carbon Dioxide is dissolved. This happens within the first hour. I would therefore be extremely hesitant to trust any "pH of 10% Sodium Sulfite" number you see. There is some discussion about this here (post 486ff)
One possibility is that someone did that and was disappointed with the results. The other is what I suggested, that the magic component, the ripening, is not initially in the formula.
Frankly, Rudeofus, I do not understand what you are trying to achieve here. We were talking about sodium sulfite quality then and now. Do you have doubts that it has vastly improved in 60+ years?If you make Sodium Sulfite from Sulfur Dioxide and Sodium Carbonate, I am quite sure it is done in a way that avoids significant left over carbonate in the final product. Even if you start with 99.999999% Sodium Sulfite, aerial Carbon Dioxide will add some carbonate very quickly. It doesn't matter, though: some fraction of percent carbonate is not going to turn a 100 g/l Sodium Sulfite solution into a decent buffer at pH above 9.
If you look at Metol in alkaline solution, it is not just some cation with half a sulfate anion: the -OH group of the cation itself is weakly acidic. This will form a neat buffer with Sulfite at a pH around 8.0 - 8.5.
if someone did a spectral analysis of the developer and figured out the ingredients
and had the mix ..
and they had some of the original mixture from bluegrass left ( they give you 2 > 2 gallon sacks from what
i remember )
maybe i am totally wrong, but as a layman not a chemist,
i am guessing that both fresh developers made with water
would yield the same results whether they were ripened or not.
( if they were in fact the same developer ) .. right?
its not the dry chemicals that are ripened but the mixed stuff.
photography companies have a long history of not giving information out to people who ask
emulsion recipes purposefully leave out steps or give wrong amounts of ingredients
and even today when people post "results" some aren't really up front with
what they did and how they got their results so things need to be taken with a huge grain of salt ..
if you like the results, why not just use the unblinking eye formula
and call it a day ... isn't that what it is all about, using a developer and liking the results?
Anyways. the lack of straight answer to my initial question is surprising, to say the least. 777's color, anyone? What are you afraid of?
Do you think it wrong to "desclassify" it after so many years? Especially as it is no longer available for purchase? What if it contained an idea worth using today in other formulas?
I don't think they're afraid of anything, I'd assume they don't exist.Anyways. the lack of straight answer to my initial question is surprising, to say the least. 777's color, anyone? What are you afraid of?
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