Is all C-41 chemistry really the same?

[Steven Lee]

I am using Kodak Flexicolor chemistry and monitoring my process with Fujifilm-made control strips. No matter what I do temperature-wise, I can't get density to be the same across RGB/CMY emulsion layers. Blue is always higher than red, and green is lower than red. Earlier I have posted my results here.

My question:

Is Fuji CN-16 chemicals are exactly the same as Kodak C-41? The control strip I am using was developed by Fuji in their CN-16 chemicals. Am I naive to expect Flexicolor to match RGB densities of Fuji's CN-16 within 0.02?

 

[foc]

In theory, they should be the same. Remember these chemicals are designed for a replenished process so any slight variances will not matter as the replenisher chemicals rep into the solution tanks.

Have a look here for some guide on control strip reading

Kodak C41 - scroll down to page 3

Fuji CN16 - scroll down to page 29

Am I naive to expect Flexicolor to match RGB densities of Fuji's CN-16 within 0.02?

IMO the answer is yes.
So long as you are within the control limits (ideally the action limits) you will be ok.

Always remember that you can't read a control strip by eye.

I ran my own minilab for many, many years. I had 3 different C41 processors from Fuji over 35 years. I have used mostly Fuji branded chemicals mainly because of the price. On occasion, I used Champion branded chemicals and swapped between the two. There was no noticeable change.

As I explained in a different post, control strips should be viewed over a period, and plotted onto a graph, that way you can see a drift and make a correction.

Again as with a replenished system, any changes are gradual and easily corrected in plenty of time. Sudden changes or spiles are usually caused by temperature fluctuations or contamination.

I know you are using one shot so extra care must be taken to keep everything consistent
Consistency is the key.

 

[Steven Lee]

@foc Thank you! I've been studying these docs for a week now, and nowhere I can find a trend where the green goes down and blue goes up :-( At this point I'll just try mixing a new batch of Flexicolor developer...