C41 Developer depletion

After getting bad results from one development session and not being sure why, I decided that every C41 development should be logged

Film surface area

The best kit I can get for C41 color chemistry is the Bellini one. It is a kit for 16 rolls of 24 exposures as per its datasheet.

Because the lifetime of the bleach, fixer, and stabilizer is higher than the developer, you can also purchase the developer part separately on the Bellini kit to “recharge” it. Everything here is talking about one bottle of the developer specifically, and not specifically the lifetime of one kit

I generally shoot 36 exposure rolls. I have the occasional roll of expired 12 exposures on hand.

If you send extrapolate these numbers, you can get a development time adjusted for the aera of film that has already been processed

Time adjustment

In theory, the C-41 process as defined use fresh (replenished continuously) developer, at a standard time of 3 minutes and 15 seconds. With these home kits we do not do that, we only have small quantity of the chemistry and we stretch it’s life.

I have not looked at the Kodak documentation to see if this is a suggested way of using the developers. I suspect it isn’t… But it is working well enough, so I would trust BelliniFoto’s data on this.

Below, I have expressed the datasheet time development as a function of the surface area of film that has been developed. These do not line up nicely with 36mm rolls. I would err on the side of going longer than shorter if I am between two of these lines

I am currently working on making myself a spreadsheet to log every single roll that has been developed by one batch of Bellini Rapid Access C-41 developer bottle. But it is both not ready yet.