Quote Originally Posted by Photo Engineer View Post
This is the port of part 1 from Photo Net posted years ago.

By now, we have 3 single layer color coatings that give us a latitude of about 2.7, contrast of about 0.5 and mid curve speed of about 100 B, 150 G, and 200 R, with threshold speeds of 200 B, 300 G, and 400 R.

We now coat a coating with R first, G, then B in a 3 layer package and we process it. What do we see? Blue looks normal, G is about 1/2 the contrast and about 1/2 stop slower, and R is about 1/3 the contrast or less and about a stop slower. The dye images look like mud. I would call it Cyan, Grape and Pumpkin. Not Cyan, Magenta, and Yellow. Something seriously went wrong.

Well, enough for now. I'll wait for comments from you all and answer questions as we go along in this thread. Lets see if there is any interest!
Film as you described it:

Sensitivity => dye layer result
200 Blue => yellow pumpkin
300 Green => magenta grape
400 Red => cyan cyan!
[BASE LAYER, not water permeable]

I take it that
1: a yellow filter layer must be underneath the blue emulsion, so that any blue light which make it past the Blue-sensitive layer can't activate silver particles in the Green-sensitive and Red-sensitive layers...because ALL silver halides are ALWAYS sensitive to UV and blue light..

Which gives us an actual structure like this:
Sensitivity => dye layer result
----------------------------------------
200 Blue => yellow pumpkin
[Yellow filter, not stated, to protect lower layers from blue light]
300 Blue + Green => magenta grape
400 Blue + Red => cyan cyan!
[BASE LAYER not water permeable]

2. Yellow came out as pumpkin due to that area of the negative being contaminated with dye formation in the magenta-producing layer.

Dynamic at work. Developer flows THROUGH the layers, starting at the top, and works its way towards the bottom layer of the film...and this effect is strongest as the developer first hits a layer, before the layer beneath it is wet... so there's really strong developer activity, producing lots of oxidized developer..but because the layer below it is still dry, a significant amount of the developer that is oxidized in the first few seconds with the top layer end up migrating deeper into the film [green layer producing magenta dye] before hitting a dye coupler. And while this isn't the majority of the developer oxidized in the yellow layer, its enough to change what should be an area of the negative with only yellow dye into one that has lots of yellow dye PLUS enough magenta to screw up our colors.

Similarly, with the magenta-producing layer... as the fresh developer first works its way the magenta layer, there is still overall drift of the water molecules through the gelatin to drag oxidized developer from the magenta-producing layer down into the cyan-producing layer, thus yielding "grape". Next, even after the magenta-producing layer is water saturated, this drift-induced effect continues because water is STILL migrating into the cyan-producing layer..

Lastly, in the bottom (cyan-producing) layer, there is no color distortion because as some oxidized developer makes its way down to the film base, well, now it's deep within the cyan-producing layer, and will have to travel all the way up to the top of the cyan-producing layer before it can possibly meet up with a dye coupler from the wrong layer...and by the time such a thing could happen, there is no longer any net directional drift of water + developer + oxidized developer through the layers, and so the oxidized developer molecules at that point

I'm assuming that after the initial water "front" reaches the film base, the effect of net drift of water + chemistry ceases to have much effect.