Fluorescence emission spectra (λ
= 366 nm) from films of gum arabic and gum arabic mixed with the five red pigments. Gum arabic shows emission at about 440 nm. Red lead presents additional emission at 580 nm, cinnabar at 610 nm, cochineal at 630 nm and brazil wood around 615 nm (intensity divided by factor 13). No fluorescence is observed with red ochre.