Diluting C41 Developer

[bvy]

I have the Rollei/Digibase C41 kit, which makes 500ml of developer. I don't presoak, so with each roll (I'm about seven in), I'm losing some volume. I now have about 450ml of working solution -- not quite enough to cover a 120 roll. I figure I need to add between 25 and 50ml of water. Can someone help me gauge by how much I'll need to compensate in development time? Or is this just a bad idea?

Thanks.

[wildbill]

presoak next time.
I wouldn't dilute it for my own work.

[Gerald C Koch]

Unlike BW chemistry processes like C-41 must be used exactly as specified. This means no dilution, no changes in temperature, and no changes in processing times. Failure to do this will result in color shifts or poor density.

[Rudeofus]

presoak next time.
I wouldn't dilute it for my own work.

Presoaking your film does exactly the same as filling up developer with water afterwards. I've heard that C41 dev kits are very robust and would assume that a little dilution is not going to hurt. A guy tried to really hit on C41 developer hard in order to achieve lomo style results, but never got those crazy colors, at least nothing that couldn't be trivially corrected post scanning.

[GeorgK]

Unlike BW chemistry processes like C-41 must be used exactly as specified.

A agree in a way that I am also not a fan of the many "great results with stupid C41 modifications"-threads on APUG.

But: C-41 is usually a constantly running machine process with a seasoned developer, defined replenishment, nitrogen burst agitation, and complex process monitoring. Home processing C-41 will always be just a rough approximation (at best). Under these circumstances, additional dilution of 10% will hardly have any (visible) effect. Especially as C-41 is quite a "strong developer" where slight variations in concentration will have only a minor effect.

@bvy:
Simply add 50ml of a.d. to your 450ml kit (do not mess with too few volume, it's not worth it). Probably add a few seconds (5-10), but not more, to avoid over-compensation.

Georg

[David Lyga]

bvy: Just for the hell of it:

Take 100ml of fresh Flexicolor developer. Dilute it 14 times to make 1500ml working solution. Then add maybe 5 grams of sodium carbonate to the 1500ml. Then, at 90F, process C-41 film for 12 minutes in as much of this working solution as you need to develop one roll, using constant, gentle agitation.

You must might become satisfied with the results, and the temp is easier to maintain.

Now, Rollei-Base is not Flexicolor, but maybe the results will be the same as mine, I don't know. - David Lyga

[bvy]

Thanks for the responses. With 400ml of developer (less than I thought), I can get coverage in my Paterson tank by placing it on its side. I have a Unicolor Uniroller transport; I'm considering sealing the lid well and placing on there, on its side, for constant rolling agitation. I would cut thirty seconds off of the development time. Thoughts?

[Gerald C Koch]

A agree in a way that I am also not a fan of the many "great results with stupid C41 modifications"-threads on APUG.

But: C-41 is usually a constantly running machine process with a seasoned developer, defined replenishment, nitrogen burst agitation, and complex process monitoring. Home processing C-41 will always be just a rough approximation (at best).

There is no guarantee that any of these home processinjg kits are anywhere near the official C-41 formulation. In all likelihood most of them aren't unless you are using Kodak's Flexicolor.

[maximgrew]

I have used slightly diluted C-41 dev from a Tetanal kit before it was also quite a bit past its 12 roll use I added around 15 seconds for the diluted old developer and you will get useable images it just depends how you feel about whats on the film really if its something you put through a holga then go for it but if not might be worth sending to a lab

and yeah with the tetanal kit you do cut 30 seconds off in a rolling processor so may well be the same for you

[bvy]

I posted that rather hastily. Hadn't considered that the tank would be outside the water bath. Still, I might just manually roll it on top of the tempered water and see what happens. And cutting thirty seconds sounds like a good idea.

And, as a matter of fact, they are Holga images. But I do have one of a semi-famous, fully pompous, operatic baritone in costume, that I'd like to see come out.