Does anyone split C41 Press Kit?

Pasto · Mar 20, 2012

I buy the 1 litre C41 Press kits from B&H. I alwaysy mix it all, giving me enough solution to process 30 4x5 sheets. However, even when I'm working on a project it could take me 2-3 weeks to shoot 30 sheets. I accumulate film till I get the 30 to process. This is a long time to wait for feedback. I'm wondering if it is OK to split the powder in the individual envelopes to make 2 seperate batches? I don't have any experience dealing with chemicals. I'm not so worried about safety issues, but rather:

1) how do I store the unused portion? How long can I safely store it?
2) How accurate does my scale need to be?
3) Do I measure 50% of the weight out of the envelope based on the label, or do I take it all out and split into 2 equal quantities?

Any other issues?
Thanks.

Trasselblad · Mar 20, 2012

I tried splitting it once. The powder that was left, when mixed, turned in to a brown, sticky and lumpy, soup and the chems didn't dissolve completely. Totally unusable. I had been storing the powders in their bags and then inside an air-tight jar but even the moisture that was left in the jar was enough to ruin what was left of the kit in about one month. It was my first kit and I had heard all the horror stories on how fast C-41 chems go off and was concerned about the longevity of the mixed liquids. Later, in my own experience, I have kept and re-used mixed C-41 press kit liquids six months after mixing, with no ill effects (until exhaustion around 15 processed rolls).

So the short of the long is: mix up the whole kit at once. Store in brown air-tight glass bottles that are as full as possible and you are good for 15 rolls or the equivalent in sheet film within six months (at least!).

Photo Engineer · Mar 20, 2012

Do not split any powder kit! Ever!

PE

Pasto · Mar 20, 2012

Understood! Thanks. I'll mix it all and store the unused portion in amber bottles. I would typically use it within a couple of weeks anyway....

Sirius Glass · Mar 20, 2012

No, what PE said.

Bob-D659 · Mar 20, 2012

Just make sure the bottles have no air above the developer. No need for amber glass, it isn't really light sensitive, but it sure eats oxygen from the air and that spoils it quickly.

dreamingartemis · Mar 20, 2012

Just a thought, if oxygen spoils it must faster, could displacing it using a can of dust off help it last longer if you cannot fill the jar to the brim?

Trasselblad · Mar 21, 2012

I don't know about the "spoiled quickly by air" statement. OK, how long is a piece of string and how long is "quickly"? As I said, I haven't had the chems go off for at least 6 months and that was without taking any special precautions, other than (plastic in this case) bottles of roughly the right size. there was still a bit of air inside the bottles. To me, temperature cycling the chemicals by only developing one roll at the time or so seems like a much more serious threat to their longevity. I have been using the Unicolor/Tetenal press kit. Maybe they have improved the formula, because the chemicals going off problem seems to be a non-problem. OK, I wouldn't leave them in a tray...

Pasto · Mar 21, 2012

When I process my sheets it's 6 - 10 at a time in a Jobo 3010. I can split the chemicals into 3 seperate set of bottles of about 300ml each and run a batch at a time over the course of 2-4 weeks. This way there is no issue of temperature cycling or of keeping properties generally. Of course I do also run a control strip at the begining of each run just because I'm paranoid, and that volume is reused but I don't expect this to be a significant source of chemical usage or deterioration....

Does anyone split C41 Press Kit?

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