After a several year hiatus, back into film and film processing. My interests in B&W chemistry have been mostly around Divided Development and the replacement of hydroquinone with ascorbate alternatives.
I decided to go where no Paul has gone before and to play with DK-50 for a number of reasons. Widely admired for many decades as a great sheet and tank film developer, it was one of Kodak's developers that had alleged magical properties by the use of Kodalk, hence the K in the name. Any alkali with the same pH and buffering capability would work as well, in reality. But that was marketing in the 1930's.
Descriptions of DK-50 have always included accolades like crisp, clean, sharp, stable, and the generic wonderful. But also, "not fine grain." Obviously, therefore, an acutance developer as the 30g/liter sulphite would imply. Yet, to this day Kodak includes lists it, diluted 1:1 in the 35mm Tri-X data sheet! Go figger.
What IS truly weird and different with DK-50 is that it uses the same amounts of Metol and Hydroquinone. Almost all other HQ superadditive developers I've ever seen use somewhere around the 1:4 ratio for maximum silver reduction per minimal chemical amount (1:9 for Phenidone/HQ developers.) And using only 30% of the sodium sulfite of D-76, it is most certainly an "acutance" developer, relatively. So who needs fine grain with a modern low or medium speed (100) film? Not I, I answered when I asked myself.
Something not often realized is that HQ has a very, almost scary, temperature/activity curve, while that of Metol or Phenidone is much, much less. I have no proof or resources to confirm my suspicion is that one of the reasons DK-50 is/was so beloved is that 1:1 M:Q ratio. This would be especially true at elevated temperatures, for whatever the reason. Behaving more like D-23 than D-72!
Then I went two steps further. I mixed DK-50 up double strength for a stock solution, but without the Kodalk. I dub thee "D-50." I split that into two bottles, one reserved for stock to dilute, and the other one for playing with as a divided developer. In fact, the latter becomes almost the same as the divided developer suggested by a Mr. Shipman back in the 1930's and revisited by Otha Spencer in Shutterbug almost twenty years ago with accolades.
So I loaded up a roll of Plus-X and went photo hunting. After shooting about half, I loaded that part into my tank and mixed up my chemicals, including a strong Kodalk stock solution for a 1:1 DK-50 soup. Four and a half minutes at 68 degrees, as I read in the Massive Development Chart, stop bath, fix. Scanned at 4800dpi, highest native, non-interpolated quality on my Canon 8800F.
Oh, my.
Where's the grain? Oh, sure, if you really blow it up, like maybe to billboard size, there it is. But if you are displaying at anything like normal print or monitor display sizes, nothing to worry about, and you get that famous DK-50 acutance. As an experiment, I also scanned it with the Canon "grain reduction" setting on Maximum, and sure enough, it smoothed it right out, what little there is. Interesting, sodium sulfite in your software! So shoot for acutance, fix grain later if needed!
Then I shot the balance of the roll. Poured in the 75 degree 2X strength D-50 stock, agitated often for 5 minutes. Poured out, poured in a pH 10.7 sodium carbonate plus some sodium sulfite solution for one minute. No agitation, just a bang on the counter to dislodge any bubbles. Poured out, rinsed with water, fixed, scanned.
Some really fine negatives........but the great ones at a fraction of the rated film speed. Certainly not what I expected or hoped for in that regard. But, a starting point for more experimentation and photochemistry fun!
For now, Im hooked on DK-50 and D-50!
I decided to go where no Paul has gone before and to play with DK-50 for a number of reasons. Widely admired for many decades as a great sheet and tank film developer, it was one of Kodak's developers that had alleged magical properties by the use of Kodalk, hence the K in the name. Any alkali with the same pH and buffering capability would work as well, in reality. But that was marketing in the 1930's.
Descriptions of DK-50 have always included accolades like crisp, clean, sharp, stable, and the generic wonderful. But also, "not fine grain." Obviously, therefore, an acutance developer as the 30g/liter sulphite would imply. Yet, to this day Kodak includes lists it, diluted 1:1 in the 35mm Tri-X data sheet! Go figger.
What IS truly weird and different with DK-50 is that it uses the same amounts of Metol and Hydroquinone. Almost all other HQ superadditive developers I've ever seen use somewhere around the 1:4 ratio for maximum silver reduction per minimal chemical amount (1:9 for Phenidone/HQ developers.) And using only 30% of the sodium sulfite of D-76, it is most certainly an "acutance" developer, relatively. So who needs fine grain with a modern low or medium speed (100) film? Not I, I answered when I asked myself.
Something not often realized is that HQ has a very, almost scary, temperature/activity curve, while that of Metol or Phenidone is much, much less. I have no proof or resources to confirm my suspicion is that one of the reasons DK-50 is/was so beloved is that 1:1 M:Q ratio. This would be especially true at elevated temperatures, for whatever the reason. Behaving more like D-23 than D-72!
Then I went two steps further. I mixed DK-50 up double strength for a stock solution, but without the Kodalk. I dub thee "D-50." I split that into two bottles, one reserved for stock to dilute, and the other one for playing with as a divided developer. In fact, the latter becomes almost the same as the divided developer suggested by a Mr. Shipman back in the 1930's and revisited by Otha Spencer in Shutterbug almost twenty years ago with accolades.
So I loaded up a roll of Plus-X and went photo hunting. After shooting about half, I loaded that part into my tank and mixed up my chemicals, including a strong Kodalk stock solution for a 1:1 DK-50 soup. Four and a half minutes at 68 degrees, as I read in the Massive Development Chart, stop bath, fix. Scanned at 4800dpi, highest native, non-interpolated quality on my Canon 8800F.
Oh, my.
Where's the grain? Oh, sure, if you really blow it up, like maybe to billboard size, there it is. But if you are displaying at anything like normal print or monitor display sizes, nothing to worry about, and you get that famous DK-50 acutance. As an experiment, I also scanned it with the Canon "grain reduction" setting on Maximum, and sure enough, it smoothed it right out, what little there is. Interesting, sodium sulfite in your software! So shoot for acutance, fix grain later if needed!
Then I shot the balance of the roll. Poured in the 75 degree 2X strength D-50 stock, agitated often for 5 minutes. Poured out, poured in a pH 10.7 sodium carbonate plus some sodium sulfite solution for one minute. No agitation, just a bang on the counter to dislodge any bubbles. Poured out, rinsed with water, fixed, scanned.
Some really fine negatives........but the great ones at a fraction of the rated film speed. Certainly not what I expected or hoped for in that regard. But, a starting point for more experimentation and photochemistry fun!
For now, Im hooked on DK-50 and D-50!