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Many are familiar with Vincent Van Gogh’s vibrant paintings, but few know that the colors we see today are not quite what Van Gogh originally painted. In fact, some iconic works appear entirely different to modern audiences from how they would have appeared to their creator thanks to the unique properties of a familiar substance: Eosin.
Why Eosin-Y?
Eosin-Y is a synthetic xanthene red dye invented in 1873 by chemist Heinrich Caro. Bright, water soluble, pH sensitive, and affordable to make, eosin-Y quickly became a preferred stain in both scientific and artistic applications. Outside of the laboratory, eosin was commercialized as a textile dye and then later sold as an artistic dye in the form of a pigment dubbed geranium lake. Geranium lake became popular with 19th-century artists for its intensity, luminosity, and wide variety of colors, ranging from orange-scarlet to bluish-red depending on the metal ion used in its precipitation.
Stomach tissue stained with H&E
Van Gogh’s Palette
Renowned for his expressive use of color, Van Gogh was particularly enamored with Eosin’s bright and bold hues. As geranium lake, eosin-Y offered a brilliant red pigment that stood out vividly on his canvases, aligning with the emotional and dynamic style of his paintings. Unfortunately for Van Gogh and his contemporaries, eosin is susceptible to fading in the presence of light and oxygen.
This photodegradation was noticed by the artist himself, who wrote to his brother Theo that “paintings fade like flowers.” To try to overcome this problem, Van Gogh followed recommendations to paint with thick, undiluted brush strokes when working with eosin pigment. However, this would only delay the inevitable.
The Irony of Light Sensitivity
Van Gogh’s masterpieces, which once radiated with more pink and purple hues, have, over time, lost some of their original vibrancy. Ironically, the very light that Van Gogh aimed to capture in his art contributed to the degradation of the eosin-based pigments in the end. This fading underscores the challenges faced by modern-day conservators in preserving the true essence of historical artworks.
The above image, created by conservators at the Van Gogh Museum, is a comparison between how "The Bedroom" appears now (left) and a digital reconstruction showing how it most likely looked when originally painted (right). [Credit: Van Gogh Museum]
Eosin in Modern Histology
Despite its light sensitivity, eosin has been the preferred counterstain to hematoxylin since its invention in the late 1800s. Its acidic properties enable it to bind to positively charged structures, providing clear and distinct contrast when used alongside hematoxylin, which binds to negatively-charged structures.
Eosin Stained Tissue
Eosin is also able to visually distinguish the cytoplasm of different cell types, connective tissue fibers, and cell matrices, by staining them in different shades of red and pink. Its enduring utility in medical science highlights the fascinating intersection between art and science, where a single pigment can play a pivotal role in both creative and analytical fields.
The Legacy of H&E Staining
Today, H&E staining remains an essential tool in histology, providing vibrant, detailed images of histological structure to assist in the diagnosis of disease states. Basic H&E staining has since been complemented by advanced staining techniques developed in the 20th century, such as immunohistochemistry (IHC), immunofluorescence (IF), and in situ hybridization (ISH).
The colorful history of hematoxylin and eosin adds depth to our appreciation of these dyes and connects the scientific world with arts and history.
Bibliography:
- Alvarez-Martin, A., Trashin, S., Cuykx, M., Covaci, A., De Wael, K., & Janssens, K. (2017). Photodegradation mechanisms and kinetics of Eosin-Y in oxic and anoxic conditions. Dyes and Pigments, 145, 376-384.https://doi.org/10.1016/j.dyepig.2017.06.031
- Bancroft, J. D., & Layton, C. (2019). The hematoxylins and eosin. In S. K. Suvarna, C. Layton, & J. D. Bancroft (Eds.), Bancroft's Theory and Practice of Histological Techniques (8th ed., pp. 126-138). Elsevier.https://doi.org/10.1016/B978-0-7020-6864-5.00010-4
- Chieli, A., Miliani, C., Degano, I., Sabatini, F., Tognotti, P., & Romani, A. (2020). New insights into the fading mechanism of Geranium lake in painting matrix. Dyes and Pigments, 181, 108600.https://doi.org/10.1016/j.dyepig.2020.108600
- Cooksey, C. (2018). Quirks of dye nomenclature. 10. Eosin Y and its close relatives. Biotechnic & Histochemistry, 93(3), 211–219. doi:10.1080/10520295.2017.141320710.1080/10520295.2017.1413207
- H01: The haematoxylin and eosin stain: from piracy to pathology. (2021). British Journal of Dermatology, 185(1), 161-161.. https://doi.org/10.1111/bjd.20155
- Titford, M. (2005). The long history of hematoxylin. Biotechnic & Histochemistry, 80(2), 73–78. doi:10.1080/10520290500138372