Thoroughly Modern: Materials and Methods presents a collection of papers that shed light on how artists embraced innovative materials born out of aesthetic modernism and industrialization. The latter especially revolutionized artistic production by introducing a variety  of new media to artists, such as synthetic pigments or commercially manufactured artist paints in tubes and household paints in cans. Therefore, multidisciplinary partnerships between scientists, conservators, art historians, and curators have become indispensable for studying the materials and output of modern artists. The collaborative efforts highlighted in this collection have illuminated the technical innovations of the time and the personal choices artists made in selecting and experimenting with new materials. The findings, brought to light through state-of-the-art scientific analysis—including microscopic, spectroscopic, and chemical mapping techniques—reveal the intricate interplay between material choices and artistic vision. These insights also provide critical guidance in crafting preservation strategies tailored to the specific needs of modern artworks, thereby demonstrating the practical implications of this research for the field of art conservation. Furthermore, the results can aid in answering questions about provenance or authenticity and dating by establishing the materials an artist used during a period in their career.

This collection of papers looks at materials used over fifty years, from the late nineteenth century to the middle of the twentieth century. Through the works of artists Paul Cézanne, Max Ernst, Piet Mondrian, Henri Matisse, Saturnino Herrán, Giorgio de Chirico, and Séraphine Louis (known as Séraphine), and through a deep look at paints marketed to artists in the 1920s, this research delves into art historical background, materials analysis, object condition, and aspects of preventive conservation. Instrumental analysis through various advanced techniques adopted or developed for conservation science illustrates how artists’ innovative use of synthetic pigments, commercial paints, and non-traditional media signaled a profound shift in both the creative process and the conservation challenges associated with their work. This insight allows us to more deeply understand and appreciate how modern artists, through their innovative use of color, texture, and function, pushed the boundaries of their media.

Early synthetic organic pigments offered artists unprecedented color vibrancy and demonstrated the coal-tar industry's capability to produce a range of pigments ready for market with varying success in light and chemical stability [1]. The use of synthetic organic pigments was evident in the analysis of commercial artists’ paints from Das Deutsche Farbenbuch (1925), where more than 80 paint hues from six German manufacturers, including watercolors, tempera, and oil paints, were analyzed to understand the chemical composition of pigments used during this critical period [2]. The analysis identified natural colorants like madder and cochineal alongside synthetic organic pigments from various chemical classes, such as anthraquinone, monoazo, and ß-naphthol compounds, highlighting this intermediate period of pigment production where naturally derived lake pigments were still widely available and in favor. This transition was also evident in Cezanne’s watercolors; synthetic alizarin and carmine lakes were noted as early as 1895 [3]. Synthetic alizarin lake was also heavily favored by Séraphine and identified across all six works examined [4]. It is important to note that the study of Das Deutsche Farbenbuch revealed inconsistencies in commercial paint labels, where some pigments were misnamed, potentially deceiving the artist about the materials used in their works. These labeling errors, or the presence of synthetic organic varieties as extenders [5], may explain how such pigments ended up in the works of Cézanne and Séraphine. Using synthetic organic pigments introduces complex conservation challenges. For instance, these new colorants may have varying levels of stability, with some proving highly sensitive to light. Paints mislabeled or containing unstable compounds could degrade unpredictably, affecting the object’s appearance and integrity over time.

Perhaps labeling was less ambiguous for Ernst, who perhaps embraced the advent of new colorants [6].  While traditional pigments like vermillion and carbon black appear in his earlier works, in his later paintings, there seems to be a shift toward using newer industrial pigments. For example, his extensive use of Prussian blue was replaced or augmented by phthalocyanine blue in 1940, a pigment synthesized as early as 1907 and commercialized in the late 1930s [7], and this perhaps speaks to his knowledge of pigment technology. Of course, the extent of his deliberate experimentation with these materials remains open and would be supported by further scientific and archival research.

Interestingly, there is a contrast that other studies touch on regarding the use of early synthetic pigments. In analyzing several works by Matisse from 1906 and the early 1910s (a period that includes his Fauvist years), natural madder and cochineal lakes were observed in the pink backgrounds of some pictures as identified by technical imaging and scientific analysis [8]. These pinks unify the composition of those works studied and perhaps speak to the consistency of Matisse’s choice of pigments given his well-doccumented preoccupation with color. Similarly, the extensive use of a cochineal lake by Herrán in his monumental mural paintings Alegoría de la construcción and Alegoría del trabajo (1910) is relatively novel in modern Mexican mural painting [9]. It potentially reflects a pre-Hispanic practice that imbued the subjects with cultural significance, predating the arrival of the better-known modern Mexican muralists of the early twentieth century. Herrán further used different pigment mixtures with cochineal lake to generate specific skin tones according to the individual’s age, gender, ethnicity, or perceived social status, in line with his practice of “Critical Art,” a style focused on the representation of the working class and indigenous peoples alongside religious syncretism.

The presence of certain pigments can be invaluable when determining the provenance and dating of objects. For example, detecting rhodamine 6G, a synthetic organic dye patented in 1892, in the Cezanne watercolor drawing The Bridge at Gardanne allegedly from 1885–86 raises questions about the dating of this work with traditional connoisseurship [3]. While the drawing is dated to the mid-1880s [10], the presence of rhodamine 6G suggests a potential later date since the dye was not available until several years after the supposed creation of the work. This discrepancy highlights the need for scientific analysis to better date Cézanne’s works, especially since he rarely signed his watercolors. This discovery also emphasizes the pivotal role of scientific techniques in re-evaluating historically accepted timelines and can have significant implications for scholarly interpretation.

Dating is especially pertinent in the case of de Chirico’s metaphysical oeuvre during the 1910s. The findings show that pigment analysis can provide valuable information for authenticating de Chirico’s work [11] given his known practice of falsifying dates and the prevalence of forgeries; even the surrealists copied his work later. De Chirico's palette during his metaphysical period was found to be consistent across many works, supporting his writings on painting techniques [12,13,14]. This palette is crucial for dating his oeuvre, especially for distinguishing original metaphysical pieces from backdated works by de Chirico, known as verifalsi [15]. For example, the absence of key pigments like lead white and vermilion in these backdated paintings and the presence of anachronistic modern pigments like cadmium yellow and Arylide Yellow (PY4) provide strong evidence of their creation in the mid-20th-century rather than the 1910s.

Dating was also a crucial outcome of an in-depth study of Mondrian’s use of zinc white in his neoplastic paintings during the 1920s and 1930s [16]. For the first time, a unique zinc white paint containing an aluminum phosphate additive was observed in several of Mondrian’s paintings created between 1921 and 1935. Given its characteristic composition, this zinc white paint serves as a marker, allowing for the dating of whole works or reworking steps in Mondrian’s process, especially since Mondrian often worked in phases. In paintings from 1921 to 1929, this zinc white paint with aluminum phosphate was usually mixed with lead white. But by the early 1930s, Mondrian transitioned to using only zinc white with aluminum phosphate, a change likely linked to the immaterial white tones he favored during this period. The study also identified another zinc white paint containing aluminum sulfate. Although the presence of this zinc white paint with aluminum sulfate was limited to just two later works in the study, it is likely that other paintings from Mondrian's later Paris years, especially those created around or after 1935, might also contain this marker paint. Identifying these additives is also crucial for interpreting overpaints during conservation treatments, especially when removing particular layers is being considered.

In addition to pigment identification, the influence of painting media is vital for understanding painting techniques and the resulting appearance of the work. Scientific analysis confirmed that Séraphine employed household paints in a highly experimental and resourceful manner. These enamel paints she used—heat-treated oils with a natural resin component [17]—played a crucial role in defining the bright, glossy finish of Séraphine's paintings. These smooth, lustrous surfaces were occasionally marked by drying wrinkles—small imperfections formed as the enamel paint dried—adding another layer of textural interest to her work. At the time, household enamel paints were more affordable and accessible than traditional artist supplies, making them a practical choice for Séraphine, who worked as a housekeeper. These industrial materials align her practice with modernist artists like Pablo Picasso [18] and Francis Picabia [19], who experimented with this non-traditional media. However, Séraphine's lack of formal training made her application of these materials particularly unique within the context of Outsider art.

Similarly, Herrán’s Alegoría de la construcción and Alegoría del trabajo reflect an experimental approach through his techniques. Scientific investigation revealed Herrán’s use of a complex multilayered painting method, combining approaches found in both traditional oil painting and murals, resulting  in a work that anticipated key aspects of the Mexican muralist movement, such as incorporating natural earth and lake pigments [20]. Technical imaging of the murals also exhibited extensive charcoal underdrawing, which is visible in several areas and provides structural clarity to the composition. Like Herrán, Ernst employed traditional media, like charcoal for frottage, the act of rubbing a textured surface to create an image, in combination with experimental techniques, to explore themes of randomness and dream imagery that evoked images from the subconscious. For example, Ernst toyed with manipulating the consistency of his oils in his later works. He introduced dripping (oscillation), a method where paint was sprayed and allowed to drip organically onto a vertically suspended canvas, forming fluid, dynamic shapes; and decalcomania, which involved pressing paint onto a surface using materials like glass, aluminum foil, or paper, resulting in random, textured patterns.

Overall, the research presented in Thoroughly Modern: Materials and Methods demonstrates how adopting and manipulating synthetic materials and industrially produced artist supplies impacted the technical and material aspects of the resulting objects. Analyzing the materials used during this time opens up new possibilities for understanding modern art during this transitional period when artists accepted new materials and exploited their characteristics to achieve various effects, perhaps in conjunction with more traditional media like some colorants for their historical significance or chroma. The tension between modernity and tradition is therefore made evident by the material and stylistic choices made by artists at the turn of the twentieth century. As such, these studies not only illuminate the technical aspects of these works but also open new avenues for understanding the cultural, historical, and technological contexts in which artists operated. The findings offer critical information for historians, curators, and conservators for understanding artworks' provenance, authenticity, and condition. These studies bridge traditional techniques and the Industrial Age’s material innovations, offering fresh perspectives on the evolution of modern art.