FWIW I just measured the RGB densities of a few of my old Kodak CP filters - kept in original cardboard sleeves and in the dark. None of them had the specified density to their complementary colour. The 50Y and 50M filters measured more like 35~40 (0.35 - 0.4D) to blue and green light, respectively. While the Cyan filters had all become near uselessly transparent. So beware of using Kodak CP filters. They haven't been made in some time, and even NOS ones are likely to have faded and be well out of specification.