Happy Thanksgiving PE,
SDA3057 IS RED. When added to an AgBr emulsion, the emulsion is magenta. Add Iodine and the emulsion turns bright lavender-cyan. My emulsions tend to be closer to white than to yellow, before addition of dye.
BTW, my last emulsion turned out to be far faster than I anticipated. I got only one panel, exposed at 1 second / f16 that was readable. I need to do the whole thing over. The panels were not fogged, as evidenced by unexposed areas showing no development.
Bill