FWIW, 2 bath development would seem to be impractical for anything like a high volume commercial line.
And many/most of the commercially packaged developers are oriented toward that sort of environment, even if that sort of environment has become rare.
I believe Photo Engineer disclosed here the secret ingredient X in Microdot-X shortly before he passed and went to the big yellow R&D lab in the sky.
For me, the first of these. The second is way too complicated. I use Paterson tanks, in which filling/emptying is very fast. But the main thing is that you always do the same, and tweak your timing if you don’t get the results you want.What is the preferred method for changing from bath A to B?
- Pour A out, then B in.
- Or: lift spiral from tank (lights out, obviously) and lower into second tank with B solution
This doesn’t make sense. Increased exposures (first sentence) means decreasing EI, not increasing EI (second sentence).Diafine instructions say: 'Because Diafine has the property of limiting highlight development, increased exposures result in higher shadow densities without "highlight blocking", thus effectively extending the tonal range. Diafine can accommodate as much as a two stop increase over the recommended indexes, without serious loss of quality." The recommended film E.I.s from the Diafine instructions are higher than box speed. For Tri-X 400 it is E.I. 1600. Why would they recommend those E.I.s if film lost speed with Diafine?
Interestingly, two-bath developers were found to have certain advantages over conventional developers when it is necessary to get "a more uniform degree of development throughout the life of a developer" as would be the case in motion film processing.
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I'd be interested in hearing your formula for "home brew" Perceptol. I once tried a formula based on the standard D-23 formula + kosher salt, and reducing the metol to 5g instead of 7.5g. It was supposedly a Microdol "home brew". In actuality, the grain was NOT Microdol grain. The secret ingredients to Microdol X have never been revealed as far as I know. but kosher salt ain't it. thank you.
Thank you @snusmumriken. I also use Paterson tanks, so...For me, the first of these. The second is way too complicated. I use Paterson tanks, in which filling/emptying is very fast. But the main thing is that you always do the same, and tweak your timing if you don’t get the results you want.
[Diafine instructions]
This doesn’t make sense. Increased exposures (first sentence) means decreasing EI, not increasing EI (second sentence).
I agree it doesn’t read well, but I think they’re trying to say two separate things: It extends the shoulder by compressing the highlights (first sentence, but not very clear), and it gives an “acceptable” quality increase in EI (second sentence). Both seem kind of plausible to me, though I’m pretty sure the instructions overstate the speed gains, and it doesn’t magically produce shadow detail where none was captured.
I guess Diafine may be where the impression that two-bath developers gain speed comes from. It used to be pretty popular, didn’t it?
-NT
I did side by side testing with Ilford packaged Perceptol and my home brew - precisely the same results. There's nothing particularly secret about it. There might be some kind of added preservative or something like that in the factory packs, but it's otherwise a basic simple MQ sodium sulfite developer plus the "secret ingredient" of sodium chloride, which they openly list ... not typical table salt, which has added things like iodine and titanium dioxide.
I can't contribute anything to the Microdol debate; but I know there are others on this forum who have home-brewed their own of that in the past; and if they choose to chime in, that's up to them.
Steve Anchell says that D-76 became the best-selling developer, not because it was the best in all respects, but because it was promoted by mighty Kodak, it became a standard. Because it was a standard, Kodak feared purturbing customers by changing it, even though it had known drawbacks. We know Kodak was aware of drawbacks because Grant Haist, a Kodak employee, formulated an improved version: D-76H.
and most importantly they disregard the evolution of emulsion technology
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