Last night I made a small batch of emulsion for the latest matrix coatings. I included 3 drops of both FD&C Yellow 5 & FD&C Red 40 to act as extinction dyes. Yellow 5 (acid yellow 23, tartrazine) has peak absorption at 422nm and Red 40 (Allura Red) at 504nm. If anyone has spectral data on the red, I'd love to see it, as it is not in the Sigma-Aldrich handbook.

I don't know how effective this amount will be; the gelatin is red, but not exceedingly so. I have no idea what Kodak's matrix film looked like with the extinction dye, or how dark it has to be. We'll see...