Having read about this in your book, was this a practice that was used to try and get different batches of particular materials closer to each other, or to prevent the scrapping of an entire master roll of coated product? Were there any products that required this treatment more than others?
I assume it was exactly the same issue we are facing. If you are not in continuous production you have batch variations and those are somewhat beyond our control. Ilford had similar problems in the end with Micrographic color. However there the amount of clients was so small that they applied fixes with the film to the few end users. Coating a filter on top to fix color shift is somethign we are currently investigating as well for Helios. It´s actually a very good aproach for the future. You never know 100% how things are unless you coat it and then its made. We will go to the market now with a separate filter but are considering a dyed topcoat.