How is C41 developer differnt from B&W?

If the job of the developer is to turn silver salts to metal, which is (my understanding) identical between color and B&W, what is the difference between a C41 developer and a B&W one?

Of course I can just grab a roll of Gold 200 and process it in Xtol heated to 100F, to see what happens. (and I should do that!) but asking here is quicker!

[EDIT] I guess I'm asking because it would be sweet to have my replenished Xtol work for both! What if there's time+temperature combination that works perfectly fine?

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.

Looks like you saved me a roll of Kodak Gold, Donald!

when you develop color film ( c41 ) in b/w chemistry there is a prominent orange mask even though its a b/w image. there are ways to remove it ( household bleach ) or other thing, or you can develop it in a strong caffenol blend and the stain from the coffee might mask the orange mask. I'd keep away from Xtol if you are developing c41 in b/w chemistry, it is a flat contrast less developer. use something that will give you contrast ( I use dektol/d72 or ansco 130 ) so it won't be a dull image.

If you want to do black-and-white C41, I'd strongly recommend just using Ilford XP2 instead of using colour film. It'll save you the step of removing the orange mask.

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?

Вormental said:

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

Click to expand...

folks have done so, although it tends to be more expensive to use. It likely would not give a strong image, and perhaps may give some staining.

I just checked the Famous "Massive development chart" and it gives a suggestion for just one Obscure film with a very long time in C-41 developer.

jnantz said:

there are ways to remove it

Click to expand...

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.

Вormental said:

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

Click to expand...

Yes, but activity is low. You could raise the pH to make it more active and use a fairly long development time. I once made a CD4-based b&w developer that worked perfectly fine. No staining etc.

koraks said:

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.

Click to expand...

I think people mean Carey-Lea silver layer when they say orange mask. This silver layer is what makes most C41 films developed in B&W chemistry appear dense. @David Lyga has a method for removing the silver layer to get better looking negatives which are great for both scanning and printing. Not sure if Caffenol can remove this layer - I doubt it. The orange tint of the negatives is hard to remove but there's no good reason to remove it. Rehalogenating bleach in Dichromate-bromide and subsequent redevelopment often changes the tint to pale yellow.

koraks said:

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.

Click to expand...

Raghu Kuvempunagar said:

I think people mean Carey-Lea silver layer when they say orange mask

Click to expand...

Back it seems in the dark ages, Larry Dressler over on Flickr in the Caffenol Palace told me he was removing the orange mask or what he thought was the orange mask. He was using household bleach (I think) but he stopped doing it after a while .. i don't remember why.. maybe it distressed his film, not sure. I do remember mentioning it to PE and I could imagine seeing him shuddering at the question ... and said it wasn't good for the film.

You're probably right koraks .. and Raghu.. maybe ? I'm no expert by any means, and my ignorance sometimes makes me gullible
With a bulletproof negative from Sumatranol130, or DcaffenolC .. can barely figure out what's on the negative, at that point orange mask doesn't really matter

Household bleach will strip off the emulsion. It'll likely not affect the dyes incorporated into the base.

John, household bleach contains hypochlorite which attacks the gelatin of the film and cause damage to it. Lyga's method uses a Blix consisting of the more benign Ferricyanide and Thiosulphate. I've used it on several C41 films and obtained very good negatives which look pretty much the same as regular B&W negatives except for the orange tint. Ilford XP2 Super though a C41 film doesn't have the silver layer and hence doesn't need Lyga treatment. It can be developed like any other B&W film in XTol, Pyrocat, Adox MQ Borax, HC-110 & even Caffenol to get very nice negatives.

Вormental said:

can I use C41 developer to develop B&W?

Click to expand...

Yes, you can. Somewhere I read about someone preferentially using C-41 color developer for a B&W microfilm stock; it produced good speed with the low contrast required to get a good gray scale from a canonically high contrast emulsion. That implies you'd need a very long development to get "normal" contrast from common B&W emulsions, however -- though as noted in another comment above, you could probably raise the pH by adding some borax or carbonate (obviously, you'd want/need to keep this developer separate from your actual C-41 developer). PPD developers are often very fine grained in character, so you might (once you find the right time) like the result.

Obviously, you'd want to avoid the C-41 bleach step for B&W film -- use regular stop bath and fixer instead (C-41 fixer, separate from the bleach, works fine, however).

C-41 color developer is also a black&white developer, however, it will be very slow for regular black&white film, because its oxidation products are not removed. When developing color film, dye couplers remove the oxidized CD-4, whereas black&white developers have no such thing. Sulfite also does not bind oxidized CD-4 very quickly, that's why all these 100 years old ultra fine grain developers are based on PPD and Sulfite, they intentionally underdevelop film.

There are two options to make C-41 CD work well for black&white film:

1. add a secondary developer like Hydroquinone+Sulfite or Ascorbic Acid. There are some published recipes for developers based on PPD and HQ/AA, and C-41 CD could be used to create something similar.
2. add a coupler compound. Possible candidates are Citrazinic Acid, 4-Chloro-Resorcinol and regular Resorcinol. The latter is less active, but much cheaper and easily available.

I've thought, recently, about adding a black dye coupler (like what's in XP-2 Super emulsion) to a color developer to get the same kind of speed gain with any B&W film that I get with bleach bypass on XP-2 Super. In my experience (originally with Kodak B&W C-41 stocks, T400CN and BW400CN, recently with XP-2 Super) you can pick up about one stop with little or no increase in grain with a combined silver and dye image vs. either one separately.

In theory, such a modified color developer ought to be subject to replenishment just as Flexicolor is -- your replenisher would have the same proportion of black dye coupler as the tank solution, or a little more (just as it has a little more developing agent).

thanks for the info and insights ! love learning stuff

Donald Qualls said:

you can pick up about one stop with little or no increase in grain with a combined silver and dye image vs. either one separately.

Click to expand...

If that were the case, staining developers would give a speed increase, but they don't. No free lunch....

koraks said:

If that were the case, staining developers would give a speed increase, but they don't. No free lunch....

Click to expand...

Staining developers don't generally stain to the point of producing a normal contrast image from just the stain after bleaching away the silver -- as is very much the case with color developer in a C-41 (or E-6) material. I've read of being able to print from just the stain image, but always with "it was challenging, but I managed it."

XP-2 is the core example here. It can produce good (not just "that's an image", but good) negatives in B&W developers, but it was intended to produce a dye image in C-41 chemistry, at full density, with the silver image bleached away. I'm in process of scanning negatives now (when I'm home) that were shot at EI800 and processed in C-41, within spec, but bleach bypassed -- and they have normal-looking contrast and density to the eye (as well as, so far, scanning well).

Now, to get normal contrast in the silver image with conventional films in C-41 color developer is likely to require extended development (especially since you're likely not to want to process at 38C) -- but doing so with black dye coupler added will gain additional density for the same exposure. How is that not a speed increase? No, not a "free lunch" because you're one-shotting relatively expensive C-41 developer (though for B&W most of the problems with @David Lyga 's diluted developer process wouldn't apply) -- but the end result is a gain in speed with (in my experience) no gain in grain. Not free, but I've got a coupon for 40% off.

Donald Qualls said:

Not free, but I've got a coupon for 40% off.

Click to expand...

I see your point; well, keep me posted. Interesting for sure, but I remain skeptical about the alleged speed gain. I do see how contrast will be helped with a substantial dye addition (as long as the dye image remains truly proportional to silver density, which should be possible), but in my experience, the toe of the curve is always the tricky bit to get enough additional density into - without additional exposure, that is.

In any case, I may pick up my experiments with CD-4 based B&W developer at some point. Not for dye-augmented development, but for regular smoothness and tonality. Initial results looked just fine and certainly promising.

Now, of course, I need to find out what serves as the "black only" dye coupler in B&W C-41 films, and hope it costs less per gram than, say, printer ink.

@Donald Qualls' idea of shooting XP2 Super at 800 and bypassing bleach in C41 processing is very interesting. I wonder if something like this would also work: first develop in your favorite B&W developer, say replenished XTol, to slightly lower than normal contrast. Stop bath, fix in C41 fixer, wash, bleach in C41-friendly rehalogenating bleach, clear/wash, expose to light and redevelop in C41 developer. This way you would be able to set the tonality using the first developer and get additional density using the C41 developer.

Wow, that's a lot of extra work, though -- but it's a classic bleach/redevelop or bleach/tone intensification (like color toning a print, which uses exactly my suggested method -- color dye coupler mixed with color developer as the toner developer, followed by a blix to remove the silver and let the color show clean). Mix the color dye coupler with color developer, and all you have to do is find the right temp/time comination, just like B&W processing a new, unfamiliar film. And you can do it with your favorite B&W film.

Donald Qualls said:

Wow, that's a lot of extra work, though -- but it's a classic bleach/redevelop or bleach/tone intensification (like color toning a print, which uses exactly my suggested method -- color dye coupler mixed with color developer as the toner developer, followed by a blix to remove the silver and let the color show clean). Mix the color dye coupler with color developer, and all you have to do is find the right temp/time comination, just like B&W processing a new, unfamiliar film. And you can do it with your favorite B&W film.

Click to expand...

You're right. For XP2 Super, the film itself provides dye coupler but one can do this with any B&W film if dye coupler is added to the color developer. Finding a suitable black coupler might be hard, but any color coupler (other than red) should be fine as we are dealing with B&W film.

Actually, red might be the best dye coupler. To enlarging paper, it looks like black -- which is exactly what we want. And red toner kits are easily obtained, not to mention I'm pretty sure there's documentation on what chemicals act as dye couplers for red in toning. Scanning isn't a major problem, most scanner software can be set to choose what color channel to build the grayscale image from; this could even be used to vary contrast after the fact in scanning (by selecting more or less cyan channel).