I think many of you would agree that DK.50 is one of the benchmark developers, and some still use it today. So, re-reading Crawley's famous series on FX developers, I found his version that he called "diluted DK.50" and presented it as a non-solvent developer. It comes at the end of the rather long list of FXs, and this intrigued me, because from the rest of his articles you would expect this developer to produce grain the size of a golf ball. I made a small portion of it, as outlined by Crawley, which is (per liter): metol 0.5 g, hydroquinone 0.5 g, sodium sulfite 6 g, potassium bromide 0.125 g. At this point I measured the pH and it was close to 7. Since I only had a "reconstructed kodalk" made in solution from borax and sodium hydroxide on hand, I started adding it piece wise, measuring the pH in the process. It came as a revelation that only 1/3 of the required volume (~3.5 g) was needed to reach pH 10. However, I proceeded to add the rest and re-measured the pH. It was a little higher but still close to 10. Then I "ripened" it by developing an entire fogged film in 0.5 L for 6 minutes. I then started to develop clips with exposure-bracketed images in the ripened portion to determine the time for box speed, which was eventually found to be 9 min at 20 C for Kentmere 100. The negatives were very nice, normal contrast and fine grained, and overall looking great, judging from the included Stouffer wedge shot on a light box.
Surprised by this outcome, I started reading other threads about DK.50 and eventually came across one posted by user "nworth", where a two-solution concentrate was cited as a "sharpness" developer, reportedly published in BJP for use with miniature film, and supposed to be used one-shot. Solution A was exactly a 5X concentrate of what is cited above, and solution B was 5% sodium metaborate. Its composition was thus identical to Crawley's version when diluted 1:1:3 with water. There is also a post by Gerald Koch to the same effect but a different way of preparing stocks. So, this diluted DK.50 contains 10 g metaborate per liter. Imagine my surprise, when I found (at Digital Truth) that "tank developer" DK.50 also contains 10 g metaborate per liter, but it is used at full strength and is supposed to be "ripened" as initially it is considered too contrasty. Now, pH of my ripened developer is still 10, so even such extreme ripening as I did does not lower the pH. IMHO it would make more sense, if instead of ripening, one would just add less metaborate so as to achieve pH 9, because there is no point in having this much metaborate in a developer claimed to be used one-shot. However, since ripening does not significantly lower the pH, it is not the factor that "mellows" the developer. Could one "simulate" the ripening process by adding chemicals that dissolve silver halide AND form a stable complex with silver? There are quite a few, but most are not in the current PF repertoire.
A later note: Looking up the Jacobsons' book, 18th edition, I found yet another version of DK.50, this time as a tank developer which is exactly 2.5 times more concentrated than the one cited above, except that kodalk is still at 10 g/L. Is this how different authors tried to guess the formula that Kodak did not disclose?
You know why I am asking this: I am looking at a legendary formula like Harvey's 777 and trying to understand how to reproduce its "ripening" without the associated voodoo (no offense intended). Isn't it actually a metol-glycin developer, in itself quite contrasty, with two silver halide solvent(s) added? If so, there could be another magical solution without the PPD.
Surprised by this outcome, I started reading other threads about DK.50 and eventually came across one posted by user "nworth", where a two-solution concentrate was cited as a "sharpness" developer, reportedly published in BJP for use with miniature film, and supposed to be used one-shot. Solution A was exactly a 5X concentrate of what is cited above, and solution B was 5% sodium metaborate. Its composition was thus identical to Crawley's version when diluted 1:1:3 with water. There is also a post by Gerald Koch to the same effect but a different way of preparing stocks. So, this diluted DK.50 contains 10 g metaborate per liter. Imagine my surprise, when I found (at Digital Truth) that "tank developer" DK.50 also contains 10 g metaborate per liter, but it is used at full strength and is supposed to be "ripened" as initially it is considered too contrasty. Now, pH of my ripened developer is still 10, so even such extreme ripening as I did does not lower the pH. IMHO it would make more sense, if instead of ripening, one would just add less metaborate so as to achieve pH 9, because there is no point in having this much metaborate in a developer claimed to be used one-shot. However, since ripening does not significantly lower the pH, it is not the factor that "mellows" the developer. Could one "simulate" the ripening process by adding chemicals that dissolve silver halide AND form a stable complex with silver? There are quite a few, but most are not in the current PF repertoire.
A later note: Looking up the Jacobsons' book, 18th edition, I found yet another version of DK.50, this time as a tank developer which is exactly 2.5 times more concentrated than the one cited above, except that kodalk is still at 10 g/L. Is this how different authors tried to guess the formula that Kodak did not disclose?
You know why I am asking this: I am looking at a legendary formula like Harvey's 777 and trying to understand how to reproduce its "ripening" without the associated voodoo (no offense intended). Isn't it actually a metol-glycin developer, in itself quite contrasty, with two silver halide solvent(s) added? If so, there could be another magical solution without the PPD.
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