Fig. 6From: In search of Humboldt’s colors: materials and techniques of a 17th-century lacquered gourd from Colombiaa FORS spectrum of a red area from the gourd, in which apparent absorbance maxima at 520 and 560 nm suggest the possible use of an organic red of animal origin. b, c FORS spectra of blue and green areas from the gourd, in which an apparent absorbance maximum at 660 nm suggests the possible presence of indigotinBack to article page