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)(posted 8533 days ago)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.