Divided developers

[nworth]

I used to use two bath developers with film a quite a bit. Everything PE says about them is true, but the variability was less than you might expect. They actually worked quite well. I have only tried them a few times in the past few years, and I can affirm that they do not work as they used to. The last paragraph of PE's original post is probably in effect. Some of the older emulsion types, like EFKE (Adox) may still work, but my attempts with newer Kodak emulsions and some newer Ilford have generally been failures.

For paper developers, I'm not sure exactly what we are talking about here. The true two bath method does work, and there are some published formulas. I've tried this method a couple of times, and it seems to work well. But why bother? You usually have good enough controls during printing so that there is no advantage, except, perhaps, with color. I did try the old Dignan divided color print system before I had a good temperature control system, and it was excellent. It had some real advantages.

The other way people talk about "two bath" developers in printing is for mixing up separate developing agent and alkalai solutions so that they keep better. (Then you combine them for a one-bath developer.) I've been using this for a few years now, and I can recommend it highly. The solutions easily last up to a year or so. Generally you mix up the developing agents with a sulfite-bisulfite buffer to keep things neutral to very slightly acid. When you add the carbonate for the working solution, you use enough extra to restore the pH. This scheme of things should work for film developers, too. But be careful here. Film development is a good deal fussier, and aging effects may be more noticeable.

 

[blackmelas]

I used to use two bath developers with film a quite a bit. Everything PE says about them is true, but the variability was less than you might expect. They actually worked quite well. I have only tried them a few times in the past few years, and I can affirm that they do not work as they used to. The last paragraph of PE's original post is probably in effect. Some of the older emulsion types, like EFKE (Adox) may still work, but my attempts with newer Kodak emulsions and some newer Ilford have generally been failures.

Do you or Photo Engineer have any comments on attempting to reformulate two bath developers for modern film. Specifically I wanted to know about Thornton's Two Bath (I just posted it and Stoeckler to the recipe area). I have used it and liked it very much. I guess PE's warning above suggests that films should be tested often. Doesn't Les in his book advocate yearly testing (or perhaps I read that elsewhere). Should we who use 2 bath developers test more often?
Best regards,
James

 

[Ole]

I read PE's remarks on modern films to mean that we should test each batch number. That makes sense - the product is unlikely to change within one master roll, but there may well be slight differences between master rolls that are not apparent with a "normal" developer.

Like lith printing and papers, two-bath developers can sometimes show up surprising differences between batches that are nowhere near measurable under normal conditions.

 

[buze]

I have been using Thornton's for some time now, and I've been very happy with the results. I tried a range of films (modern Ilford, and some chinese) and it works exactly as advertised...
His article indicated that it was a reformulation targeted at modern film...

 

[juan]

I test papers for incorporated developer. The last two
tested were Forte Polywarmtone and Kentmere Fineprint.
Not a trace.

Have you tested the three papers you've mentioned?
My method is to expose then develope with a carbonated
only solution; a certain real world test. A gram in 125ml
of water will do a 5x7. Dan

I have relied on what the manufacturers have said about the papers - for Ilford, the claim of incorporated developers is in their published data, for Kentmere Bromide, the information was in an email to me from the manufacturer.

For Polywarmtone, the information is available on the JandC website and the Forte website.
juan

 

[Gerald Koch]

There is a subtle difference between "divided development" and "two bath development" for films and the two terms should not really be used interchangeably.

In a divided developer, the developing agents are present in the A bath and the activator in the B bath. The pH of the A bath is such that practically no development takes place in the A bath.

In a two bath developer, some development may take place in the A bath since it is usually a slow working low alkalinity developer such as D-23. The B bath contains an activator which then speeds up the development process started in the A bath. In this system the goal is for bath A to provide density while bath B provides contrast.

Development of papers first in one developer (usually a low contrast one) and then in a second developer (usually a high contrast one) is termed "split development" and is something different again.

This ticket has managed to really muddy the water with regard to development.

 

[kwmullet]

Thanks Gerald.

Cogent and concise. I learned something, too.

-KwM-

 

[dancqu]

There is a subtle difference between "divided development"
and "two bath development" ...

In a divided developer, ... the activator in the B bath.

In a two bath developer, ... The B bath contains an activator...

This ticket has managed to really muddy the water with regard to development.

Not so subtle water bath, no activator. Dan

 

[dancqu]

I have relied on what the manufacturers have
said about the papers.
juan

Any include developer may be no more than a technicality.
By no means should one assume that all that is needed for
development is a tray of carbonated water. Some very little
amounts are reported to affect contrast. Super coats with
DI may have so for the purpose of emulsion longevity.

My interest in testing for DI emulsions is to confirm
that there is present no amount sufficient to in any
way participate in image formation. Too easy to
test per my previous post. Dan