Color from BW processing....

[fotoobscura]

So there's a backstory to this so I'm not instantly discounted as insane:

I have several hundred rolls of Kodachrome in various forms KP25,40/64. Sometimes I have fun with them and shoot a roll or two and clear off the remjet and see what I see.... Better than throwing them all away and it piques my curiosity...

Every once in a while I get color, by processing via BW. That is, I process in bw, usually stand develop for a few hours in a tsp of Rodinal, clean off the remjet and then run it through my Nikon at a 24 or 48b rgb scan.

This time around I got color that was fairly accurate. Thinking that was a coincidence I went through the (negatives) and found another color also represented (mostly) accurately. E.G. red came out orange, and blue came out, say, turquoise....An incandescent bulb came out orange/yellow..

Is this a coincidence or is something setting up here? Or is it my scanner being creative?

P.S. I've had this happen using C41 film as well but only once and never recorded how I did it...

Thanks

 

[Prof_Pixel]

Kodachrome film raw stock (unlike the C41 film you mentioned) does not contain color couplers. It does contain a yellow filter (very fine Carey Lea silver) that I suppose might cause some yellow coloration of the developed image (if it's not removed by the fixer).

 

[Rudeofus]

I can imagine oxidized p-Aminophenol couple with C-41 color couplers, but as already mentioned by Prof_Pixel, for Kodachrome you'd also need the right couplers being present at the right place, which sounds a bit unlikely. What I could imagine instead is an interaction between blue/black density created by Rodinal development and the embedded constant density yellow filter. This concept would nicely explain the yellow/orange light bulb image, and it could explain a dark faintly cyan colored object surrounded by neutral bright area (after the scanner software performed automatic color correction from blue/black object with yellow bright surroundings), but it would not explain normal looking color images.

Is there a chance you could post some of these scans?

 

[Photo Engineer]

The sensitizing dyes can remain in the coating and it could be imagewise. I guess this could cause faint color.

 

[Athiril]

Never tried Kodachrome, but when I inspected b&w developed colour film that's been stopped but not fixed, there is very visible colour showing on a colour patch chart. Which seemed to disappear after fixing.

 

[Rudeofus]

Never tried Kodachrome, but when I inspected b&w developed colour film that's been stopped but not fixed, there is very visible colour showing on a colour patch chart. Which seemed to disappear after fixing.

Which seems to confirm PE's statement, that sensitizing dyes can cause color effects on B&W developed Kodakchrome. Since I assume that fotoobscura properly fixed his film, these dyes should be gone, but maybe fotoobscura only got these color effects when the fixer came close to exhaustion ...

 

[fotoobscura]

Which seems to confirm PE's statement, that sensitizing dyes can cause color effects on B&W developed Kodakchrome. Since I assume that fotoobscura properly fixed his film, these dyes should be gone, but maybe fotoobscura only got these color effects when the fixer came close to exhaustion ...

Interesting observation. So perhaps I have not be able to reproduce because I fixed with nearly exhausted chemistry. But somehow fixed "enough".

I have shot another roll using color wheels and colorful scenes that I will develop soon. SO far I am somewhere in the 90% confidence range that I am getting color and it's not a fluke. I literally have images where blue shirts are blue, red is red, using BW chemistry scanned RGB.

Thanks for everyone's input. This is very valuable/interesting to me.

FO

 

[fotoobscura]

I can imagine oxidized p-Aminophenol couple with C-41 color couplers, but as already mentioned by Prof_Pixel, for Kodachrome you'd also need the right couplers being present at the right place, which sounds a bit unlikely. What I could imagine instead is an interaction between blue/black density created by Rodinal development and the embedded constant density yellow filter. This concept would nicely explain the yellow/orange light bulb image, and it could explain a dark faintly cyan colored object surrounded by neutral bright area (after the scanner software performed automatic color correction from blue/black object with yellow bright surroundings), but it would not explain normal looking color images.

Is there a chance you could post some of these scans?

First, thanks for your analysis. I will post some of these scans today/tonight. I think you have nicely summed up the likelihood of what's happening here, at least for the C41. I have an image from years ago (my first experience with this behaviour) that I will post shortly.