No-formaldehyde stabilizers/rinses – looking back

[AgX]

In the year 2000 Kodak substituted their C-41 Flexicolor Low Formaldehyde Stabilizer with their Final Rinse without formaldehyde.

Agfa however listed a no-formaldehyde stabilizer for their AP70 process as early as 1993/94.

And what about Fuji?

Were in all cases the changes due to a change in magenta-forming coupler or were other means employed as a different aldehyde substituting formaldehyde?
The fact that Kodak advises to treat their E-6 films in case of cross processing still with formaldehyde indicates that Kodak employed a change of coupler (seemingly not appropriate for their E-6 films.)

 

[bob100684]

Whenever they switched from the XX2(chemical concentrate, lab tech mixed) series film processors to the XX3(chemical cartridge "just add water) series procesors.

In the year 2000 Kodak substituted their C-41 Flexicolor Low Formaldehyde Stabilizer with their Final Rinse without formaldehyde.

Agfa however listed a no-formaldehyde stabilizer for their AP70 process as early as 1993/94.

And what about Fuji?

Were in all cases the changes due to a change in magenta-forming coupler or were other means employed as a different aldehyde substituting formaldehyde?
The fact that Kodak advises to treat their E-6 films in case of cross processing still with formaldehyde indicates that Kodak employed a change of coupler (seemingly not appropriate for their E-6 films.)

 

[AgX]

Thanks Bob,

But is your answer concerning the time of switching referring at Fuji?


And there is still my question by which means did Agfa and Kodak (and in case Fuji) could get rid of using formaldehyde as a stabilizer?

 

[Photo Engineer]

Well, first off C-41 dyes are not meant to be viewed by people, just print materials, so the colors are not an exact match for the human eye as is the E6 dye set! Second, more research goes into C41 and ECN dyes due to the much larger market. So, there have been more advances in negative, masked dye sets and print dye sets than in reversal dye sets.

Second, some stabilizers use Sodium Formaldehyde Bisulfite, an odorless form of Formaldehyde that releases the formalin in the coating. This is used in the E6 pre-bleach. So, from a stability standpoint, modern E6 and modern C41 are not compatible.

PE

 

[AgX]

Sodium Formaldehyde Bisulfite...

Well, it took me a moment to realize that it is the sodium salt of methansulfonic acid.

Less harmful than formaldehyde. And less volatile I guess…

Well, first off C-41 dyes are not meant to be viewed by people, just print materials, so the colors are not an exact match for the human eye as is the E6 dye set.

But as dyes have to fit, either the human eye and its receptors or the sensitizing agents in the paper, not much tolerance should exist in both cases. (Though in the latter case one could try to respond with the paper design to slight changes in the design of C-41 image forming dyes.)


In some Fuji films there are a surprising number of protective layers on top of the film. Could that be related to a stabilizing issue?

 

[Photo Engineer]

Well, first off, Sodium Formaldehyde Bisulfite is really what is called an adduct. It is not exactly the Sodium salt of Methanesulfonic acid, and is made (AFAIK) by a different route.

It is a white powder at room temperature, with no odor and dissolves in water freely. It releases CH2O on being treated to a pH change.

Don't forget that C41 dyes are masked with Azo coloring groups or DIR agents and so differ from E6 couplers and print couplers. Print couplers are designed for extreme stability.

Overcoats usually contain UV absorbers and free radical inhibitors. Since Kodak has the patents on these in the emulsion layers or attached to the couplers, I assume Fuji uses a different method.

PE

 

[bob100684]

Thanks Bob,

But is your answer concerning the time of switching referring at Fuji?


And there is still my question by which means did Agfa and Kodak (and in case Fuji) could get rid of using formaldehyde as a stabilizer?

The first frontier systems came out in the late 90's. Formalin was replaced with "a proprietary anti-fungal agent". I'll get you an ingredient list from the MSDS at work.