Why not 2 baths developer only?

[Raghu Kuvempunagar]

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.

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.

 

[Raghu Kuvempunagar]

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.

And nobody seems to have followed up the idea subsequently in contrast to the copious interest the subject generated prior to the disclosure.

 

[snusmumriken]

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

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 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?

This doesn’t make sense. Increased exposures (first sentence) means decreasing EI, not increasing EI (second sentence).

 

[MattKing]

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.

View attachment 405469

I could certainly see how two bath developer modifications could be applied for motion picture film development - those long reels of film run in high volumes through the machines.
But commercial labs that develop many short rolls of film - that would be more of a challenge.
Unless the labs were able to approach them the same way as Kodachrome - many customer rolls, all spliced together into a long single roll, run through the machines, and then separated at the end back into single rolls.

 

[Milpool]

Salt is in there but the secret ingredient in Microdol-X was Chlororesorcinol according to Ron Mowrey (from a conversation with Richard Henn). Henn had worked on this at Kodak in the 50s/early 60s in an effort to find additives to extra fine grain developers that would prevent problems like dichroic fog on emulsions in those days. The two Henn/Kodak patents are online.

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.

 

[bernard_L]

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.

Thank you @snusmumriken. I also use Paterson tanks, so...
In the meantime, I found this post from 2013 by @David Allen

Roll Film AGITATION - Thornton's Two Bath

I have been working with Thorton's Two Bath Developer (120 roll film on stainless reels) for the past couple of months. I have had excellent luck so far and am settling into an agitation pattern. I have The Edge of Darkness and have done quite a bit of "web" reading on this developer. I am...

www.photrio.com

that is very clear. Strangely it came out of a google search, but is not found by photrio's advanced search, despite giving all the relevant keywords.

Now to develop my first roll of Aviphot200...

 

[DREW WILEY]

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.

 

[ntenny]

[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

 

[snusmumriken]

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’ve never used Diafine. The only developer that I have used that genuinely seemed to increase speed (about half to one stop with Tri-X) was Emofin. I loved using it at the time (it’s now discontinued), but grain was coarser than with Thornton’s.

 

[Paul Howell]

"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?"

In the 60s and 70s Diafine was pretty popular. The Sacramento Union a paper I freelanced in the 70s for always had a quart kit on hand for pushing. At the time Trix was rated at 2400 in Diafine. I recall posts here where folks clamming to push Trix to 3200 by running the film though for a cycle, then a long wash, and back though again. I have not tried the the tech. Most shops carried it along with it's stable mate Acufine. UPI kept in stock as well, but the printers disliked printing as the negatives were soft and hand be printed at a higher grade. Up until the 90s prints for the wire or half tone had to be somewhat higher contrast. I normally print at grade 2 or 3 depending on the paper used, with Diafine I print grade 3 or 4. I have a 5 or 6 rolls shot in the last 8 months that were developed in Diafine, I think I will try to split grade print.

 

[Sidd]

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.

Would you please share your home brewed Perceptol receipe?

 

[ntenny]

I used to get pretty good mileage out of Diafine with Efke IR film. It didn’t seem to change the effective speed, but the highlight restraint kind of reined in the Wood effect, resulting in images that were a little less aggressively “Look at me! I’m infrared!” I imagine the same thing would happen to some extent with current IR films.

-NT

 

[halfaman]

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.

D-76H is Haist effort to probe that only one developing agent is needed to formulate a developer, an idea he was an advocate of according to PE. It is at best nor better neither worse than Kodak official D-76, besides a probable shorter shelf life.

 

[DREW WILEY]

Sidd - I'm not trying to take business away from Ilford. But there can be times packaged Perceptol isn't available; and its formula has been posted before (though sometimes with typos).

Per liter of stock solution :

metol 5 g
sodium sulfite anhydrous 100g
sodium chloride 30g

Optional if you get streaking issues due to water quality (I've never needed it) :
3.5 g sodium tripolyphosphate water softener
or else 0.2g EDTA

As usual, start with about 350ml of hot water, and dissolve just a pinch of sodium sulfite to it before mixing in the metol, then afterwards the balance of sodium sulfite as well as sodium chloride. Finally, top off with water to 1 L.

I suspect the unlisted trace ingredient is simply a sequestering agent in the two pack kit to facilitate mixing, and completely unnecessary if the sequence I noted above is followed.

 

[Lachlan Young]

and most importantly they disregard the evolution of emulsion technology

I think the thing that really comprehensively knocked two-bath development on the head was the discovery of development inhibition effects in their various forms. At a stroke it enabled better highlight control, and a much better speed/ grain/ sharpness relationship in a manner that allowed consistency at scale, rather than the sensitometrically vague guesstimates of various developer influencers in the popular press of the day. The thing that never ceases to amuse me is people who simultaneously spend their time muttering about why they don't like XP2 Super (at least when developed properly in C-41), yet spend dozens of pages declaiming about how their concoctions dredged and regurgitated from popular magazines of the mid-20th century produce compensating effects, without realising that unless the characteristic curve of their efforts matches XP2's, it ain't a compensating developer...