slide film in C-41 - orange mask?

[grommi]

Hi everybody,

I like to develop slide film in C-41. I always get an orange mask as with regular color neg film, but E6-developed slide film of course doesn`t have such a mask.

Is there an explanation and a way to remove the mask with cross-developed slide film?

Thanks in advance and best - Reinhold

 

[Rudeofus]

That orange mask is an integral feature of C-41 film and not part of C-41 developer. It is formed by very special color couplers embedded in C-41 film which don't change from colorless to dye (as in slide film, and some oddball C-41 films), but change color during color development, and thereby create much improved overall color reproduction.

Obviously such an orange mask is not present in slide film, therefore you must be seeing some form of dye fog from cross processing. You can check whether that base density goes away if you add some Acetic Acid or Potassium Bromide to C-41 CD whenever you develop slide film with it.

 

[georgegrosu]

It is not clear for me notion of the mask.
You mean density of fog or the color correction mask?
I developed ~ 10 years ago some tests with Provia 400
in ECN 2 process.
ECN 2 is a kind of 41 C for color negatives whom.
Mention - Provia 400 was expired 4-5 years.
The negative color came out is a little fog.
The fog was ~ 0.2 and had a purple tint.
The fog was no yellow - orange as a color negative.

George

 

[John Salim]

There is a way to 'minimize' this mask a little in colour negative film when cross processing through E-6 and that's by up-rating then push processing by 2 stops.
This helps blow away the ( reversed ) dark blue cast to a lighter blue cast.
Unfortunately you'll never get rid of the cast completely and results tend not to look too attractive.

Also, different films can give very different results.

For the best looking 'cross processed' images, always use E-6 through C-41.

John S

 

[grommi]

The mask looks more or less the same as the one from color neg film, so it`s a clear orange brown tint. Sometimes, with long expired films, some base fog is added and the color turns to dark brown. The latter is no surprise, but why has fresh slide film in C-41 dev this mask at all?

Wouldn`t adding any acid to the developer make it unusable? Isn`t the proper pH very delicate thing?

Thanks again - Reinhold

 

[Rudeofus]

The mask looks more or less the same as the one from color neg film, so it`s a clear orange brown tint. Sometimes, with long expired films, some base fog is added and the color turns to dark brown. The latter is no surprise, but why has fresh slide film in C-41 dev this mask at all?

Again, this is no orange mask, whatever color you seem to have on your film. Orange mask is a special dye coupler which absorbs some part of the light spectrum by itself, and for which reaction with oxidized color developer only changes which part of the light spectrum gets absorbed. Such couplers are neither used nor useful for E-6 film.

If you see non-trivial base density after C-41 processing of E6 film, then you see basic developer fog, i.e. C-41 CD erroneously develops unexposed silver halide grains and forms dye in their vicinity. The only way to address this is reduction of C-41 CD activity, preferably in those layers which show the most base fog. This can be done by lowering pH, or by adding restrainer.

Wouldn`t adding any acid to the developer make it unusable? Isn`t the proper pH very delicate thing?

Developer activity of typical color developers changes with pH, i.e. if you lower developer pH carefully, you can reduce developer activity base fog while mostly retaining film speed. Start with a few milliliters of Acetic Acid 80% (or equipotent amount of less concentrated Acetic Acid) per liter of C-41 CD and see what happens. If you have access to Iodide and Bromide, you could even fine tune the color balance of your cross processed film, Iodide acts mostly in the outer most layers, whereas Bromide acts more evenly on all layers. You can check your film's data sheet to see in which sequence your film's color layers are coated.

 

[georgegrosu]

I do not know other documentation for the effect of pH variation on the process of tratement negative color ECN 2 than Kodak.
http://motion.kodak.com/KodakGCG/uploadedfiles/motion/h24_08.pdf
The range of variation of pH to within ± 0.2 units to developer.
To a decrease in pH of developer ECN 2 with 0.2 units, low minimum density is about 0.02 of density.
Larger decrease occur at maximum densities around 0.2.
Most falls yellow.
There is a chance of an unbalanced color of film.
The few ml of conc. acetic acid might decrease the pH of more than 0.2 units.
When things are the results is more unpredictable.
Regarding potassium iodide was used in b&w developer in the Orwochrom 9165 process.
Potassium iodide reduced yellow fog (for ORWO films).
Potassium bromide reduces the fog on three layers, but this can lead to an increase in image contrast.
I do not really understand why you wish to reduce the fog on film?

George

 

[gzhuang]

Strangely, I only see a green mask on my crossed processed E6 film.

 

[georgegrosu]

Now I'm starting to understand what you mean.
If it's a color that covers as a filter all densities tell dominante and can correct the picture.
I call the dominant color.
If the image is dominant in the open and another color
dominant in closed area then tell unbalanced color.
Picture can be corrected only in photoshop.
You have to appreciate what you have.
Dominance or color balance.
Seems a dominant color.

George