action of color chemistry on color film...

Hello all,

This may have been discussed before, and if so, I apologize. Please redirect me to the right thread or posting. If not...

How does the color chemistry act on individual layers of the color emulsion without interfering with the other layers that were already affected in previous steps of the color development process?

Is there a tutorial somewhere that explains this clearly?

Thanks,

Bob Mazzullo

In C-41 and E-6 color processing, the chemistry "acts" on all layers of the film simultaneously. The color couplers that produce the dyes of the image are all "developed" at once. They are constructed of molecules that do not migrate from layer to layer, thus the dyes formed stay put. Hence, there is only one color developer in E-6. and only one developer in C-41.

Now, if you are talking about K-14 Kodachrome processing, then someone else will have to reply..as this film actually does have individual layers developed separately.

Bob;

If it is C41, there are no steps prior to color development. At that time, diffusion comes into play and the layers begin developing in the order; yellow, magenta and then cyan. The layers have separator layers between them as shown in my post elsewhere, which isolate oxidized color developer to the layer it belongs in and prevents migration.

If it is E6, then the negative silver is done by the time color development starts and only the positive silver is developed forming a positive dye image. This process goes to completion. Again, interlayers prevent wandering of the oxidized developer and therefore prevents cross contaminations.

So, there are no 'previous steps' in color development except in Kodachrome, and that specific layer wise development is kept isolated by selective re-exposure which is described in many places here.

There is an excellent article on the whole thing by Chuck Woodworth of EK, who has posted this on (I believe) howthingswork.com. I'm not sure of the exact URL for this, but a google will find it for you.

PE

Perfect...now I get it!

Thanks, guys....