I am in a photo class, and have access to only the black and white chemicals. Could I process color film this why? I know that it would not be color, but black and white. Any info would be helpful.

-- Jacob Abshire (bilbob@uswest.net), February 08, 2001

Answers

Yup, you can. You will have to fiddle with the developing time. A good place to start is with the developer's time for an equivalent B&W film. Be ready for some weird results though. The negatives will have an orange cast from the masking layer. They will not be as sharp as standard B&W negs and probably won't be permanent. For goofing around tho', color film is often much, much cheaper than B&W.

Good luck

-- Duane K (dkucheran@creo.com), February 08, 2001.

Surely the orange mask is chromogenically generated too? B&W developer shouldn't produce the orange compensating mask. I don't see why the images would be less permanent either. The image will be silver, not dye, the same as ordinary B&W.

-- Pete Andrews (p.l.andrews@bham.ac.uk), February 09, 2001.

I have to stand corrected - Pete is right - the orange masking layer is a dye-coupled layer that will not develop a color in B&W chemistry. I'm at work now so I can't look at the negatives to see if there's a color cast or not. If there is, I'll post an addendum.

I suggested that the negatives may not be permanent because of the additional layers and unknown effects from the B&W chemistry. The silver image should be stable though.

Cheers,

-- Duane K (dkucheran@creo.com), February 09, 2001.

The orange mask is not chromogenic. If it was, it would vary as you varied development. And that would not be good.

Anyway, to make sure, I just fixed a cut off piece of Kodak Gold 100 (WAY out of date). The film is orange.

-- Terry Carraway (TCarraway@compuserve.com), February 09, 2001.

Hmm, this is getting deeper and darker... Goes to show what I know - I don't do any work with c-41 film - just B&W. All I did was develop one roll of C-41 film in B&W chemistry (which I can't even find now.) :o)

I now think that the masking should be chromogenic because it has to complement one or more of the other colors, ie., if it were everywhere why not use an orange filter when printing?

OTOH, reading C-41 film documentation also talks about a yellow filter layer needed to prevent the deeper layers from responding to blue. Maybe this is the layer that Terry sees.

-- Duane K (dkucheran@creo.com), February 12, 2001.

Duane,

The orange mask isn't a mask like a contrast mask, more like a filter. The color of the film is orange, not yellow.

As to why not just use an orange filter, I have no idea, however different films have different colors and densities of orange.

I will have to pull out some of my in depth color chemistry books.

-- Terry Carraway (TCarraway@compuserve.com), February 13, 2001.

In a fit of insomnia I dug thru a book on photographic processes. While it doesn't detail C-41 in particular, it says that the color negative's orange cast is caused by the combination of the uncoupled dyes of the two lower layers (yello & cyan?) (The direct quote is much longer & I'm going from memory) I believe this to mean that the orange mask is not present where there was exposure and subsequent dye coupling, but I could be wrong.

I still couldn't find the sample of C-41 film I developed in B&W chemicals. I seem to remember that it didn't have any color at all - I had hoped for something weird and wonderfull but ended up with a less than sharp B&W negative. It's possible it faded away and so I turfed it.

Terry, let's hear what your books have to say.

Cheerios

-- Duane K (dkucheran@creo.com), February 13, 2001.

Duane,

We are both sort of right. According to "Photographic Color Printing" the colors are there before development, but change during development creating a mask.

The cyan and magenta image layers are imperfect, in that they react to more than just the desired wavelengths of light. So there needs to be some complimentary color masking to get better, truer color rendition. So the dye couplers in those layers are colored (red for the cyan layer, yellow for the magenta layer) in the base film stock. During development, the dye couplers are used in proportion to the amount of the desired color image density. So in the cyan layer, the more cyan exposure of a given point, the more red dye coupler is used, reducing the red color at that point. But where there is no cyan exposure, the full red color of the dye coupler remains.

So, the orange color is there before development due to the red and yellow colored dye couplers. This is what I saw by fixing some color film. But the MASK is produced during development by changing the density of the red and yellow in proportion to the amount of cyan or magenta exposure.

Voila, both of us are right.

BTW if you did this with old film (prior to 1949), you would not see an orange mask, because that is the year that Kodak introduced this.

-- Terry Carraway (TCarraway@compuserve.com), February 17, 2001.