CS-41 Chemistry Test

[toejam]

Is there a strip test method for CS-41 chemicals? I developed 3 rolls and hoping to still use the chemicals once I finish a few other rolls.

 

[Sirius Glass]

Is there a strip test method for CS-41 chemicals? I developed 3 rolls and hoping to still use the chemicals once I finish a few other rolls.

I have developed up to 14 rolls with 1 liter kits of Unicolor C-41 chemicals, however I do it in a 1 to 3 day period as quickly as I can to avoid any color shift problems.

 

[koraks]

Is there a strip test method for CS-41 chemicals?

Only with control strips and a color densitometer. Which is for the home user a more costly approach than just buying fresh chemistry.

 

[mohmad khatab]

Only with control strips and a color densitometer. Which is for the home user a more costly approach than just buying fresh chemistry.

+1

 

[AgX]

Well, one could print a neutral grey, from a respective negative on test strips. And then use a processed strip for visual control against a respective older or initial strip.

As a colour analzyer is adjusted by visual control of prints anyway, this should be good enough. For what the OP has in mind, just realizing of a deviation.

 

[Rudeofus]

Only with control strips and a color densitometer. Which is for the home user a more costly approach than just buying fresh chemistry.

These process control strips cost less than 1€50 a piece, which is below the cost of chemistry even for a home brewer like me.

 

[koraks]

Great. Now show me the €25 color densitometer.

 

[Rudeofus]

Great. Now show me the €25 color densitometer.

That densitometer costs several hundred Euros. BTW just looking at the processed test strips tells me, whether I am at least in the ball park.

 

[koraks]

Well, that's promising. Honestly, I cannot really judge color accuracy from color negatives at all. I really need to print them for this.

 

[Sirius Glass]

Only the first 4 are free of color shifts. The other 10 aren't. Source: the inventor of C-41.

That is not what Unicolor states in its instructions. Up to 12 rolls although FreeStyle told me and 16 rolls. I have done 16 rolls but I develop them all within two or three days.

 

[MattKing]

That is not what Unicolor states in its instructions. Up to 12 rolls although FreeStyle told me and 16 rolls. I have done 16 rolls but I develop them all within two or three days.

@Sirius Glass and how do you reconcile the fact that a giant chemicals company like Kodak couldn't figure out how to get more than 4 rolls from 1L of CD4 (with a warning to drop to 3 for ISO 800 films!), but a small no-brand team managed to quadruple that number? Moreover, the army of chemists at Kodak couldn't make a blix work for C41, yet seemingly a dozen of tiny chemical manufacturers suddenly solved it and started selling blix-based C41 kits?

I will admit though, that I haven't done a decently controlled / instrumented comparison.

The answer is a word that is close to the heart of all moderators - "tolerance(s)".

 

[Sirius Glass]

@Sirius Glass and how do you reconcile the fact that a giant chemicals company like Kodak couldn't figure out how to get more than 4 rolls from 1L of CD4 (with a warning to drop to 3 for ISO 800 films!), but a small no-brand team managed to quadruple that number? Moreover, the army of chemists at Kodak couldn't make a blix work for C41, yet seemingly a dozen of tiny chemical manufacturers suddenly solved it and started selling blix-based C41 kits?

I will admit though, that I haven't done a decently controlled / instrumented comparison.

The developed rolls were as Matt said with in tolerance to make good prints. Perfect conditions are only reached at absolute zero and insanity whichever comes first.

 

[foc]

I have found that eyeballing a control strip and noticing a change usually means that it is very much out of control.
The densitometer lets you know the subtle changes and then you can make the corrections to keep within limits.(that is provided you want to be within limits)
Densitometer for accuracy.
Eyeballing for flying by the seat of your pants.

 

[MattKing]

All of your rolls in that 1L batch after the 4th came out with a color cast, you just did not care.

They may not have colour casts per se, but they probably have issues with crossover and contrast behavior in different parts of the images that is different than optimum.
Whether or not those issues have a marked effect on the appearance of any prints or any digital scans will vary with circumstances.

 

[Sirius Glass]

You may be OK with the results you're getting. But it is not OK to falsely state that you avoided "any color cast issues". You have not. All of your rolls in that 1L batch after the 4th came out with a color cast, you just did not care.

Greg, like it or not, the manufacture states it is OK to do at lease up to twelve rolls, FreeStyle says that they consistently do up to sixteen rolls and I usually do fourteen rolls. I do not do 16 rolls because I usually do not have that many.

 

[MattKing]

Unicolor are significantly more tolerant (there is that word again) of performance variation than the manufacturers of the films and commercial colour chemistry.
Which is fine, because so are many/almost all of their customers.

 

[sillo]

I always cringe a little when I see someone say how their c41 kit lasted 1+ year or they developed 40+ rolls and they were all "perfect."

 

[Sirius Glass]

I always cringe a little when I see someone say how their c41 kit lasted 1+ year or they developed 40+ rolls and they were all "perfect."

I would not know, I have never used a C-41 kit beyond three days, actually rarely as long as two.

 

[brbo]

My C-41 kit always lasts me 1+ year, I process 50+ rolls with it and all my negatives print perfectly. Or "perfectly".

Fuji rates the kit for more than that, but what does an Instax company know about developing film...

 

[sillo]

That’s the 5 liter kit though? I was talking about 1 liter press kits.

 

[brbo]

Point is, Fuji somehow believes it's possible to develop more than 4 rolls with 1L of C-41 developer. Nuts!

 

[Sirius Glass]

Point is, Fuji somehow believes it's possible to develop more than 4 rolls with 1L of C-41 developer. Nuts!

Well some of us do not accept what Old Gregg says on face value.