2-bath devs and time / agitation?

I use two baths when I am too lazy to use strictly controlled bw developing (like ZS).
Thornton's version of Stoeckler formula and Tetenal's Emofin are two which I use most.

'common internet knowledge' says that 2-bath developers are easy, doesn't care about temperature, time or agitation. Ofcourse many of us know that some, like D-23 cares. At least some degree. Emofin also seems to care, as the datasheet suggests fast agitation especially for push developments.

Knowing that, I happened to leaf through the book 'The Ansel Adams Guide, Basic Technologies Of Photography, Book 2' by John P. Schaeffer.
At page 91 the writer states that result of divided developer was indentical when film was developed using Jobo at 68°F and 80°F. The used developer is not mentioned clearly. It was possible D-23, but could be Farber AB too.


That's a bit confusing. Emofin's develop times varies by temperature (according to datasheet). I have impression that results of D-23 derivatives varies as time or temperature changes. The agitation method also affects the result of D-23 derivatives, I presume?

How is that actually?

I use a replenishment type two-bath and have used Thornton's. I always process at 20 centigrade so can't comment on temperature issues. However, time does definitely effect the final result and is relted to film speed: lower speeds require less time and higher speed films need more. For Delta 400 rated at 200 I process for 4 minutes in each bath agitating every 30 seconds.

Hope this helps,

David.

www.dsallen.de

I don't know anything about the composition of the baths in Emofin, but I have used several two baths, including Thornton's. The Thornton formula and other D-23 based two baths include an accelerator in the first bath. This means that development does take place in that bath, and temperature will have an impact. I reduced this impact by splitting the sodium sulphite that you are supposed to put in the first bath (80g/L) in half and putting half in bath A and half in bath B.

You can avoid this altogether by using a two bath like Diafine which does not have any accelerator in the first bath.

Time has passed and I have read a lot of about two bath developers and especially about D-23.. It's a wonderful world where you realize that a lot of things you have read before are common miss understandings that spreads along the literature


With D-23 and it's variants, the first (A) bath controls highlights and second (B) bath controls shadows. So the developing times and agitation really matters.

Actually, I didn't realize earlier that original D-23 (single bath) is exactly same as 1st solution (or A bath) of divided D-23.
So the A bath works like ordinary D-23 stock solution, the given developing time is just shorter.

That is kind a confirmed in Ed Buffaloe's article on Unblinking Eye, where he quotes Veenstra:
As I use (there was a url link here which no longer exists) of Stoeckler's divided D-23, I begun to wonder...
I expect that Thornton's version will have similar behaviour with original D-23, despite having less metol and sodium sulphite in A bath.
In the B bath, borax is replaced with sodium metaborate. According what I have read, it should give bit more grainy and contrasty result as borax.

Actually Dead Link Removed idea works exactly like divided D-23, with most(?) developers.

Pity that I haven't have enough time for testing


Assuming that everything above is right, then how could Thornton and many other say that one liter of solution A will last for 10 to 15 rolls of 135 film? My current understanding is that either bath A should be replenished or time in bath A should be correct after each developed film. Running so many as 10 rolls with same A bath should not give consistent results (as I haven't yet used this developer for very controlled developing, I wasn't aware of that).

If that I have understand everything right, then... would the diluted 1+1 or 1+3 one shot solution for A bath be practical? Will diluted solution have enough energy to develop highlights even with D-23 variants that have less Metol and bit lower alkalinity?

Agitation in two bath developers is very imporatant. For many years the makers of Diafine published a pamphlet on how to use their developer. They warned that not following their agitation method would result in poor results. This may be the reason why some love this developer and others hate it.

It is imporatent to know whether some development can occur in the first bath. For such developers agitation and temperature are more important than if there is little or none. An example of this case is divided D-23 where development does occur in the first bath.

Nothing is free in photography, there is always a price. Two bath developers distort the tonal range of the subject by changing the characteristic curve. The speed increase often claimed with their use is largely hype.

Using two bath developers should not be an excuse for sloppy technique. The factors that determine a good negative when using a conventional developer still apply when using a two bath one. While two bath developers have their use, people who use them for the sole reason that they are too lazy to agitate a conventional developer or use a thermometer should go digital.

My experience with the two bath (Thornton, D32, and other variants) is that is is great for N- development, where you can get good shadow separation while reducing the overall density. I've used D23 to normal development and used the various second baths to bring out shadow details. This worked although the overall negative density increased significantly. For TriX, 8 min D23 and 4 in Borax 1:1 20C was a nice combination using minimum agitation, about 3 inversions/2 minutes. Seems no matter what developer tangent I'm on (currently on another FX-2 and FX-37 tangent) I go back to this combo.

The capacity claims for the Thornton formula are reasonable. Assuming 1 x 135-36 = 1 x 120 = 3 x 5x4 sheet, I have processed over 10 films per litre. The limiting factor is usually Bath A losses from film absorption and tank carry-over reducing the volume too much.

Metol is reasonably linear in behavior with temperature changes, but I aim for a consistent 21 C. I normally use a Jobo, but no pre-rinse, so it pays to have the developer at the right temperature.

I have yet to see a speed increase, and wouldn't expect to see one.

I am still working out the balance of my first and second bath times to get just the right behavior for me. At least the recommended times in the literature are usable

Graham

Chris: Am I reading this right - "For TriX, 8 min D23 and 4 in Borax 1:1 20C was a nice combination using minimum agitation, about 3 inversions/2 minutes." Does that mean D-23 1:1 for eight minutes and then Borax for four? That sounds like something similar to Thornton's - a longer time but greater dilution. For Thornton, I use either metaborate or 18 g borax to 1 ltr. Is your borax solution similar to this? Sorry for the bother.

Modern film do not seem to work well in divided solutions. The emulsion being to thin to carry much in bath two. I did tri x and Plus for decades and they worked well. No luck with modern emulsions. The best I could do was with doubling the metol concentration.

Agitation has little effect in A, be careful not to wash A from film in B. Fast films require more time ,slow less, as a rule of thumb.