You’ll read in the old literature about the “color” of negatives and how to achieve the best density. Since the process is mainly sensitive to UV light, the more “warm” color negatives give the best density for printing.
Sutton and Mudd talk about using certain chemicals to achieve a “red” or “brown” negative. If you look on the visual light spectrum, you’ll see that red, or “brown” would block more (UV) light than a neutral color (gray/black). There are ways to achieve this in development and fix. I’ve always gone for the “red” negatives. They print really well and look great!
Collodion Dry Plate Negative photographed on my light table - 5600K and not adjusted.