Pre-washing and 2 bath developers

I've made up my own 2 bath developer which I would like to try out, part A has a pH of about 3-4.


I would like to keep and re-use part A as it contains the developing agent.


One of the films I like to use is Shanghai GP3, if anyone here has pre-washed with it, they know the discarded water comes out a heavy dark blue.


I can only imagine how opaque it would get after only a few runs with GP3, other films do other colours too.


I would like to avoid colouring bath A, and conserve bath A for as long as possible.


I've yet to test it and make adjustments to the amount of developer in bath A.



Has anyone pre-washed here with 2 bath developers?


The developer should still permeate the emulsion and displace the water right? So no problems?

Athiril,

I imagine you are correct. However, you should probably drain the film thoroughly before transferring to bath A to minimize carry-over and you will have to leave the film in bath A longer to ensure that the emulsion is as saturated with developing agent(s) as possible. This should be easily determinable with a test (same pre-soaked film, several different bath A times; minimum time in bath A is when you can tell no difference in density at a longer time. I don't think you will need to adjust the amount of developing agent in the bath).

That said, I'm don't think the anti-halation dye will damage your bath A. You might make up two A baths, and use one with a pre-soak and one without for a while to test this as well.

Best and have fun.

Doremus Scudder
www.DoremusScudder.com

Do NOT prewash with a 2 bath developer. The first bath is not absorbed properly into wet film.

PE

PE - wouldn't a prebath on and 2-bath developer simple need more time in the first developer bath as you would need the extra time for the water to diffuse out of the film and the developer to diffuse in?

It's not productive (i.e. faster or better) but it wouldn't ruin the entire process.

Kirk, I assume that the individual has times worked out for this developer. Using a prewet with a 2 bath developer is one of the few conditions of using a prewet that will change the times utterly. So, you are right, but to be honest, I don't suggest it. It depends a lot on the "sucking action" of dry gelatin and the composition of part A.

PE

That is what is my thinking by logic... but then I thought, how can a 2 bath developer work well at all if what the film soaks up is so easily displace, ie: after intial agitation, you may have displace nearly all the developer, which is mixed homogenously with the base into a now very dilute weak solution not capable of developing? So I figured it mustnt displace that much and have been running tests so far without pre-washing.

The way I see it, you'll be changing the nature of the gelatin by making it already wet. You will slow down the absorption of the first bath considerably, and no matter how hard you try there will always be some water left over in the tank. Over time, this will continue to dilute the first bath, changing its working properties as well. Seems to me that what you're considering is the perfect way to de-stabilize what should be a very consistent process. Next question is, of course, why would you even worry about carrying over any anti-halation dyes? They will do no harm, and might even bleach out in the developer. Seems kinda silly to me. I use Diafine, a commercially prepared two bath developer that can be used many, many times over. Both baths have discolored to the point where they really look nasty, but it doesn't matter one bit. The stuff works the same as it did when it was freshly made over a year ago. I replenish it from time to time according to the manufacturer's directions and it just keeps on going.

i've currently ran about 2 gp3 rolls through a two bath developer and there is no blue residue nor colour in the A bath. my A bath consists of metol 6.5g/L and sodium sulfite 50g/L.

ps. the only film i've ever had an affect of colour on the A bath was fuji Acros but never saw any adverse effects on the film itself. i've kept an A bath going for over 6 months of various sodium sulfite levels (35g/L to 80g/L) and never experienced any discernable change in development. there is no real reason to avoid the colouring of the A bath.

It's an interesting point about the dye though. At home, I have hard water. In the darkroom, I use a water filter. When I use a two bath developer, I tend to not get much if any dye from the film. When I use a one bath developer, I tend to get little or no dye. When I use the same film but develop at school, I get dye from the film from both the two bath and the one bath developers. The only difference I can tell is that I filter my water. Try it, it might make a difference if the dye bothers you.

See "How the developer works"
www.largeformatphotography.info/twobath
Your developer has a low pH,there would not be any development in the first bath,after a pre-soak the film could be left in the first bath for as long as it takes for absorbed water to be displaced which would have to be found by tests.
This would not be the case with a first bath of higher pH where the time in the first bath affects the development.