Document Type
Article
Publication Date
4-29-2026
Abstract
Three colorants were studied in this project: indigo, cochineal, and ultramarine. The synthesized and naturally sourced version of each color were compared qualitatively and quantitively. All colorants underwent extensive physical and chemical analysis including, UV-visible, infrared, reflectance, and X-ray fluorescence spectrometry and high-performance liquid chromatography. Finally, a qualitative survey was conducted with the advanced and experimental painting classes at Longwood University. Synthetic and natural indigo performed identically in spectral testing; however natural indigo extract produced vibrant blue fabric while synthetic indigo produced green samples. It was found that the cochineal extract purchased from Shepard textiles was treated with alum and performed identically to a carmine red standard and differed from the expected carminic acid standard. Cochineal was the least identifiable paint sample with a 47 ± 20% percent identification rate of the natural vs synthetic pigments. French Ultramarine, which is, the synthetic ultramarine, exhibited an increased reflectance peak at 450 nm compared to natural ultramarine, indicating a brighter blue color. Synthetic ultramarine had a sulfur peak in X-ray fluorescence that was three times greater than natural ultramarine, also supporting a brighter blue color. Ultramarine was the most identifiable color with natural ultramarine having an identification rate of 87 ± 10% and synthetic identification rate of 84 ± 7%. Overall, it was determined that synthetic colors generally produce a more vibrant color in paints and dyes due to the purity of the compound.
Recommended Citation
Corbin, Bryant, "The Chemical Nature of Colors: Exploration in Variance Between Natural and Synthetic Colorants" (2026). Longwood Senior Theses. 50.
https://digitalcommons.longwood.edu/senior_theses/50
