How is C41 developer differnt from B&W?

[cmacd123]

I dont think so. Most or all of the orange mask is incorporated in the base; no way to get it out without destroying the film itself.

Why does this keep coming up. Color film has a Grey or slightly Blue base. the orange colour comes from Yellow and Magenta couplers in the film which correct for dye absorption. Don't believe me? take a scrap colour film end and scrape off the emulsion like you were going to make a splice.

 

[Athiril]

4-aminophenol (stuff in Rodinal) is a type of colour developer, and I would say metol is too, and possibly phenidone. They all have amine groups which results in dye formation. But only when there is no or very little sulphite in the developer. I havent tried since much playing around about 10 years ago. But I shot a colour card (RGB and CMY) and developed on some C-41 film and developed in Rodinal, stopped and rinsed, and inspected the film before fix. The colour is very visible on the surface of the film, from memory both bleach and fix and just fixed removed 98% of the colour. I did a few experiments to try and enhance and increase the colour and then bring it in out post scanning as well. Its strikingly visible prior to bleach and fix.

It needs some kind of mordant to fix the dye and protect it I guess. I have another idea to convert the Rodinal into a colour developer, Ill try it when I

get some analog equipment again.

 

[Athiril]

No no no I'm perfectly fine doing proper B&W and proper C41, but my curious engineer's brain just wanted to know. Donald answered my question perfectly, thank you everyone.

Although now I'm curious about the opposite: can I use C41 developer to develop B&W?

If you're looking for something to play with, Rodinal 1+100 stand for 10 minutes prior to C-41 dev boosts shadows slightly. Extending that further to 15 or 20 minutes would help more I would think. And combining that with pre-flash and pushing the C-41 hard would be something, havent tried it, Ive tried each on their own. Pre-flash with pushing is quite effective when you hit just the right pre-flash amount.

Here is some Superia 800 @ 12800, C-41 dev time of 6 minutes, 38 celsius iirc.

-3 preflash (tissue double folded over in front of lens, metered through tissue for 12800, exposed 3 stops below meter, then normal exposure at 12800 after it - as a double exposure on top of the preflash) - same as no pre-flash

-2 preflash

 

[Athiril]

Why does this keep coming up. Color film has a Grey or slightly Blue base. the orange colour comes from Yellow and Magenta couplers in the film which correct for dye absorption. Don't believe me? take a scrap colour film end and scrape off the emulsion like you were going to make a splice.

Curious if you have tried fixing a piece of C-41 film with no development on it?

 

[Donald Qualls]

4-aminophenol (stuff in Rodinal) is a type of colour developer, and I would say metol is too, and possibly phenidone. They all have amine groups which results in dye formation. But only when there is no or very little sulphite in the developer.

This effect -- formation of dyes on oxidation -- occurs with at least p-aminophenol and metol; that's what you're seeing when old developers turn brown with time. The dyes that form are slightly weak in cyan/blue, so the overall color is yellow/brown. I'm rather surprised you can see the colors in unbleached C-41 film, however; I'm pretty sure the dye couplers in the emulsion aren't correct for the dyes formed by developers outside the PPD family. Might be that the dyes are weakly coupling and the bleach breaks them loose from the couplers, allowing them to wash out. You might (if/when you get back to it) explore using a formaldehyde based stabilizer before bleaching. This used to be a required step (though, with correct dye couplers, applied after bleach and fix steps, as part of the final rinse) for C-22, and C-41 until around 2000.

Of course, it might also be that the dyes are coupling to the developed silver some way, which gets removed during bleach and fix -- but that wouldn't explain getting roughly correct-looking colors (the dyes should be random in that case, producing a brown or black image).

Obviously, this isn't going to replace proper CD-4 based color developer, but it's a cool and interesting "this gave an image" sort of finding...

 

[Athiril]

This effect -- formation of dyes on oxidation -- occurs with at least p-aminophenol and metol; that's what you're seeing when old developers turn brown with time. The dyes that form are slightly weak in cyan/blue, so the overall color is yellow/brown. I'm rather surprised you can see the colors in unbleached C-41 film, however; I'm pretty sure the dye couplers in the emulsion aren't correct for the dyes formed by developers outside the PPD family. Might be that the dyes are weakly coupling and the bleach breaks them loose from the couplers, allowing them to wash out. You might (if/when you get back to it) explore using a formaldehyde based stabilizer before bleaching. This used to be a required step (though, with correct dye couplers, applied after bleach and fix steps, as part of the final rinse) for C-22, and C-41 until around 2000.

Of course, it might also be that the dyes are coupling to the developed silver some way, which gets removed during bleach and fix -- but that wouldn't explain getting roughly correct-looking colors (the dyes should be random in that case, producing a brown or black image).

Obviously, this isn't going to replace proper CD-4 based color developer, but it's a cool and interesting "this gave an image" sort of finding...

Those two examples were scanned as a reflective iirc. Given the file name of the first one, it appears I would have developed, bleached and not fixed.

 

[Rudeofus]

There is a non-trivial chance, that sulfite destroys the dyes you created that way. It would be interesting to see, what remains of these dyes, if you fix with pure Sodium Thiosulfate, or even with Sodium/Potassium/Ammonium Thiocyanate.

 

[Donald Qualls]

Those two examples were scanned as a reflective iirc. Given the file name of the first one, it appears I would have developed, bleached and not fixed.

Okay, so the colors we're seeing there are dyes against the milky halide, probably.

There is a non-trivial chance, that sulfite destroys the dyes you created that way. It would be interesting to see, what remains of these dyes, if you fix with pure Sodium Thiosulfate, or even with Sodium/Potassium/Ammonium Thiocyanate.

I'd recommend adding some ammonium chloride to the plain hypo, or using a two-bath fix; plain hypo alone won't fully fix tabular grain, which includes all or almost all modern color films.

 

[Rudeofus]

If plain hypo is fresh, it will fix high iodide film just fine, it will only take longer and its capacity will be poor. Ammonium Chloride might speed up fixation, but it will not solve the capacity problem. The experiment can also be done with Ammonium Thiosulfate, but it would be very important, that it contains little to no extra sulfite.

 

[David Lyga]

Color developers are generally poly-phenylene-diamine (PPD) derivatives that produce specific oxidation products that bind with the dye couplers in the film layers to produce very specific colors of dyes, with density proportional to the amount of silver developed. Once the developed silver is bleached (usually back to a halide of some sort) and the halide fixed away, all that's left is the image formed by the dyes.

Xtol will give you an image, but it'll be three or four layers of B&W negative image, without a hint of color, because neither phenidone nor ascorbate produce the cocrrect oxidation products to bind to the dye couplers. Then your blix or bleach and fixer will remove the silver image, leaving you with blank film (just as would occur if you put black and while film through a C-41 process, because there are no dye couplers in the emulsion). You might be able to get a faint wrong-color image if you use a PPD-based developer, but few if any B&W developers use this developing agent because of its low activity, low contrast, and higher toxicity than metol, phenidone, or even hydroquinone.

Your responses are always exceptionally succinct, unambiguous, and always readily understandable by non chemists like me. - David Lyga

 

[Donald Qualls]

I give all credit to Ron Mowrey, Photo Engineer, who explained that in some detail several years ago. My only contribution is rephrasing.

 

[Вormental_old]

EK still has hundreds of chemists working there, right? I only wish some of them frequented photrio... This knowledge isn't lost, it's just not (hopefully temporarily) easily accessible with Ron's passing.

 

[MattKing]

EK still has hundreds of chemists working there, right?

I don't think EK has hundreds of any type of particular expert any more, and they certainly don't have hundreds of people working with photographic film.
They are a commercial printing manufacturer who still have a a small division dealing with a small portion of their legacy photographic history.

 

[Beverly Hills]

Your responses are always exceptionally succinct, unambiguous, and always readily understandable by non chemists like me. - David Lyga

Hi David - it's a bit fateful, missing a few hours at school and you can never make up for the missed chemical class.

Btw : .......the wether in Philadelphia is it " still rather cold " in town? !!!

seriously : you have to think your way through it, at first you don't understand anything and little by little you understand more and more .....!!


Best wishes to you in Philadelphia , David !

 

[Beverly Hills]

Color developers are generally poly-phenylene-diamine (PPD) ........[...........,]. ..,.You might be able to get a faint wrong-color image if you use a PPD-based developer, but few if any B&W developers use this developing agent because of its low activity, low contrast, and higher toxicity than metol, phenidone, or even hydroquinone.

.......remember PPD was a very early developer agend in the past. It was indeed from very low activity ! But combined with metol as a second agend it became very popular during the 20s/30s. A high-tec extra fine grain developer then!

( PPD is indeed very harmful )

 

[koraks]

Best wishes to you in Philadelphia , David !

I second that.
I also hope David will rejoin us one day here on Photrio. He hasn't been around for a while.

 

[Donald Qualls]

combined with metol as a second agend it became very popular during the 20s/30s.

There was a developer known as 777 that combined PPD, Glycin, and Metol, IIRC, and could be self-replenished indefinitely -- it was very popular with portraitists because of its tonal rendering and extremely fine grain (both greatly enhanced after extensive seasoning).

 

[Beverly Hills]

There was a developer known as 777 that combined PPD, Glycin, and Metol, IIRC, and could be self-replenished indefinitely -- it was very popular with portraitists because of its tonal rendering and extremely fine grain (both greatly enhanced after extensive seasoning).

....right, I have it in mind! But a good time before there was a popular one : named Methol extra fine grain I can't find the formulation but I have it somewhere ....hope....