CN-41 Developer Storage

RedSun · Jan 21, 2015

Since I just turned on my 2nd fridge, I've decided to store my CN-41 developer part C in the fridge. The temp is about 33F. I put the bottle inside a clear plastic bag for spill protection. The bag is not air tight.

Just want to make sure that I do not miss anything. I can't manage to get the inert gas into the bottle. Also, I do not like to divide it into several small bottles with fear of contamination from not perfectly clean bottles.

Not sure how long the part C can last this way. 3-5 years?

David Lyga · Jan 21, 2015

With Kodak's Flexicolor C-41, I believe that the parts A and B are the vulnerable ones, if my memory serves me correctly. Maybe it is the same with the brand that you have. If so, the C part is not vulnerable to oxidation (correct me if I am wrong). Thus, store it at room temp in a PET plastic or glass bottle. The A and B must be stored air-tight, however.

When stored this way, it keeps forever, and at room temp. But you must be almost obsessive with how well you keep the A and B from oxygen. Years and years of storage of the opened concentrates, but stored airtight in either PET plastic or glass, prove me correct. - David Lyga

RedSun · Jan 21, 2015

David, you got is the other way. It is the part C that goes bad. It can oxidize and becomes black.

Gerald C Koch · Jan 21, 2015

As a general rule it is not good to store photo solutions in the frig. Certain components may crystallize out and be difficult to re-dissolve. Better to store them in a cool, dark place What is more important is protecting the solution from oxidation. Use only glass or appropriate plastic bottles like PET.

David Lyga · Jan 22, 2015

RedSun said:
David, you got is the other way. It is the part C that goes bad. It can oxidize and becomes black.

Thank you RedSun. I get this sometimes mixed up, as the RA4 developer is the opposite. THAT (RA4) part C is not susceptible to oxidation. With C-41 it is the A which is able to be stored without worrying about oxidation. Again, thanks.

Right, Gerald, storing in the refrigerator is not necessary, ever, in my experience. - David Lyga

RedSun · Jan 22, 2015

I have some very old sealed CN-41 kits (> 10 years?). Both A and B are still very clear, but the C is like very old coffee. When I tried to mix it, the C becomes flakes in the water. But the bleach and fixer in the same batch work just fine.

The RA developer I have is a one-part only. But it looks like oil floating. Instruction says to mix the developer concentrate well before mixing water. It is old, but is still working just fine.

David Lyga · Jan 22, 2015

The C, as you correctly stated, RedSun, is the most vulnerable. Honestly, it can turn darker than black coffee. However, if it is not FULLY black, it actually can still be used and there will be little difference in the outcome of the developer. My advice is to measure off a little and use a like proportional amount of the other chemicals (A and B) and see how it goes. The ratios for the C-41 Kodak Flexicolor concentrates are as follows (for a 25 gallon kit: KF 12-1532753):

A: 7568ml
B: 888ml
C: 946ml

Thus, we have, approximating, but almost exact, the following proportions:

A: 8 parts, B: 0.94 part, C: 1 part

Hope this helps. - David Lyga

Simonh82 · Jan 22, 2015

I have stored part used C41 part C for about 18 months and the batch of replenished working solution developer for about 30 months now, both in the fridge. I'm extended dev time to 4 minutes and it is still working well, at least for scanning where minor colour variations can be corrected easily.

I think I also squirted some butane lighter gas in to the bottle before capping it. This is in the original Rollei C41 chemical bottles which I think are HDPE. The working solution is kept in PET plastic drinks bottles with the air squeezed out.

CN-41 Developer Storage

Privacy & Transparency

Privacy & Transparency