C-41 processing problem

[liamhart93]

Hi,

Ive been experiencing some problems with C-41 development and hoping somebody can help.

Im using a colenta roller transport machine (data sheet here: http://www.colenta.de/color/filmprocessors/datasheet ar 30 c41 30.pdf) with a tecnolab replenishment unit and it works perfectly, negatives processed through it are clean, correct exposures and no problems at all.

The problem I've been having is after around 3 weeks of new chemistry going in (developer in particular) the negatives start to go thin and under developed.

Im using tetenal ergoline colour developer and all my other chemistry is tetenal, what Im wondering is, is this a chemistry problem? Im suspecting that it is and if so, is this just expected from tetenal chemistry? Or is there another problem that im doing or could be happening?

The machine is on and in use 5 days a week, some days will be 2/3 films and others can be 20/30 films, could this also be problem?

I have some knowledge on this but am fairly new and inexperienced to c-41 processing myself. Would appreciate any help at all from anybody.

Thanks,

 

[Sirius Glass]

I have heard and read that about two weeks is the usable lifetime for C-41 developer. Longer for the bleach and Blix. I do all my processing in two or three days at most.

 

[EdSawyer]

what does the developer look like at that point? Sounds like it is exhausted and/or oxidized.

 

[liamhart93]

Developer is a dark red colour, which confused me as shouldn't be should it?

Im guessing its exhausted, but from what I've read and the leaflet I received with the developer, it should be able to do a lot more films than whats been done.

Oxidization could be it too actually, would this cause a colour change in the developer? Or any other signs?

 

[Photo Engineer]

Under replenishment can cause this problem. If you could plot control strips you would see a gradual shift in density with time.

It could also be oxidation during idle time. You would see the same shift from control strips.

At some point, you are not adding enough replenisher and this might be true for all solutions.

PE

 

[liamhart93]

Thankyou for both your replies this has helped me a lot.

I have seen that gradual shift in density but haven't thought it could be due to under replenishment. The chemicals Im using are ergoline tetenal and supposed low replenishment rate chemicals and I have set the machine and replenishment unit to slightly above what tetenal reccomended due to some advice, do you think I should try replenishing more?

Thanks,

 

[Photo Engineer]

Sounds like it, but without test strips (control strips), I cannot really say.

PE