Andy Warhol and His Amazing Technicolor Shoes: Characterizing the Synthetic Dyes Found in Dr. Ph. Martin’s Synchromatic Transparent Watercolors and Used in À la Recherche du Shoe Perdu

Abstract

Synthetic organic dyes were extensively used by artists in the first half of the 20th century, knowingly or otherwise. This included Andy Warhol and his À la Recherche du Shoe Perdu (c. 1955), a major portfolio of hand-colored prints, a copy of which resides in the collection of The Museum of Modern Art (MoMA). Warhol and his friends were known to use Dr. Ph. Martin’s Synchromatic Transparent Water Colors to bring these prints to life. A historical set of Synchromatic Transparent Watercolors were initially investigated by UV-visible spectroscopy, and samples from the historic set were also characterized by µ-Fourier transform infrared spectroscopy for fingerprint identification. To better elucidate the nature of the mixtures present, thin-layer chromatography was coupled with surface-enhanced Raman spectroscopy to separate the components of all colorants in the set. The dyes decisively identified include Acid Red 73, Acid Red 87, Acid Red 17, Acid Red 103, Basic Red 1, Acid Orange 7, Acid Yellow 23, Acid Green 1, Basic Green 4, Acid Blue 3, Acid Blue 93, Basic Violet 3, Basic Violet 10, Basic Violet 17, and Acid Black 2. Overall, Acid Blue 3, along with Acid Orange 7 and Acid Black 2, were found in the greatest number of dyes in the Dr. Ph. Martin’s set. Data from the historic set was subsequently used for direct comparison with reflectance spectra from the Warhol portfolio using principal component analysis. Microfade testing on a Synchromatic Transparent Watercolors brochure was also conducted to identify fugitive colorants, the results of which were extrapolated to each of the prints in the Warhol portfolio. The analysis provided further insight into the dyes used in À la Recherche du Shoe Perdu and confirmed the extreme light sensitivity of some colorants and the fastness of others.

An Introduction and Recent Advances in the Analytical Study of Early Synthetic Dyes and Organic Pigments in Cultural Heritage

“…Databases containing a wide range of FORS spectra of SOPs are available [29] and the Istituto di Fisica Applicata Nello Carrara of the Italian National Research Council (IFAC-CNR) created an online database of reflectance spectra of traditional and synthetic pigments [69]. FORS has been applied to identify ESDs and SOPs in powders and paint tubes belonging to Fernando Melani and Lucio Fontana (1899-1968) atelier materials [70,71], in oil paintings [72,73], prints [74,75] and historical textiles [25,32,[76][77][78][79]. The technique has limitations due to a relatively poor wavelength resolution (ca.…”

“…To summarise, FORS more commonly identifies the chemical classes of these molecules (as proven for trialrylmethanes, xanthenes, phthalocyanines, Hansa Yellows, quinolines, etc.) [29], whereas other techniques are required to confirm the identifications at the molecular level and check for the possible presence of mixtures [32,74,75,77].…”

“…Both benchtop and portable instrumentation are available, the latter being valuable when pigments must be pinpointed in artworks characterised by wide chromatic areas [112,113]. Raman spectroscopy performs very well for the identification of SOPs in reference and historical atelier material [91,110,114,115], in drawings and paintings of modern artists [33,74,80,92,93,97,106,110,[116][117][118], in plastic design objects [119] and sculptures [120]. The main limitation of the Raman spectroscopy is the background fluorescence signal produced by the organic matrix or support.…”