The Walters Art Museum Shines a Light On the Toxic History of Medieval Manuscripts

"If Books Could Kill" reveals the deadly history of manuscript production and the impact on bookmakers’—and readers'—health.

If Books Could Kill, Walters Art Museum, 2025, Installation View.
An installation view of “If Books Could Kill” at the Walters Art Museum. Courtesy of the Walters Art Museum

Attention bibliophiles and antiquarians: did you know that some old manuscripts are downright deadly? In modern society, it’s entirely safe to browse through books, but for centuries, flipping through the pages of a single tome could have devastating health consequences, as toxic chemicals were often used in their creation. The Walters Art Museum in Baltimore is digging into this lesser-known side of bibliology in “If Books Could Kill,” which looks at the dark and dangerous side of the production of illustrated manuscripts and other texts.

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It’s not a large exhibition, but it’s a versatile one, covering medieval bookmaking technology and science, the social lives of books and contemporary conservation science. It also explores the life stories of the book illustrators who suffered from various maladies after extensive exposure to toxic materials.

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“When I first came to Walters, there were only four manuscripts created by women, and I was interested in women’s engagement in manuscripts,” Dr. Lynley Anne Herbert, who co-curated the exhibition, tells Observer. “When I got Clothilde Missal, a manuscript illustrated by Clothilde Coulaux, I found it surprisingly heavy.” When she asked the museum’s book conservator why it was so weighty, she was told that “the heaviness came from the beautiful creamy white colors, which are full of lead.”

Treatise on Elephants, 1824; Ink and paint on paper bound between, The Walters Art Museum, Gift from Doris Duke Charitable Foundation's Southeast Asian Art Collection, 2002
Treatise on Elephants, 1824; Ink and paint on paper, Thailand, gift from Doris Duke Charitable Foundation’s Southeast Asian Art Collection, 2002. Courtesy of the Walters Art Museum

Neither Dr. Herbert nor the book’s dealers had known that the book contained lead, and that discovery prompted her to consider the impact daily work with toxic materials might have had on Coulaux’s health. As it turns out, a substantial number of medieval manuscripts contain toxic materials such as white lead and red mercury, which were both common pigments used during Coulaux’s lifetime (1878-1931). The exhibition reveals how these and other toxic materials were used by scribes, artists and bookbinders and showcases twenty-four rarely displayed examples of beautiful but dangerous manuscripts from the Walters Art Museum’s extensive collection.

There’s cross-cultural representation here, as Europeans weren’t the only ones using pigments created with arsenic and other toxic materials. “If Books Could Kill” has plenty of geographical and chronological range—there’s the 19th-century Treatise on Elephants from Thailand with its arsenic-based yellows and a 15th-century copy of the Armenian Gospels with vermillion pigments made with cinnabar.

Gospels, Lake Van, Turkey, 1455; Ink and pigments on thick paper folios with rounded outer edges bound between wooden boards lined with coarse red linen covered with thick red goatskinAcquired by Henry Walters, 1911
Gospels, 1455; ink and pigments on thick paper folios with rounded outer edges bound between wooden boards lined with coarse red linen covered with thick red goatskin, Lake Van, Turkey, acquired by Henry Walters, 1911. Courtesy of the Walters Art Museum

This exhibition also offers a rare behind-the-scenes look at the work of conservation scientists. While some toxicants can be identified by sight, others are only revealed through scientific testing. A conservator-led video in the exhibition demonstrates how portable X-ray fluorescence (pXRF) is used to identify the mercury in the heart shapes embellishing the pages of one illustrated medieval manuscript.

“I’m a huge fan of gloves, not only when handling these books but many other things, really,” conservation scientist Dr. Annette S. Ortiz Miranda, who curated the exhibition with Dr. Herbert, tells Observer. “Don’t touch any of the colored parts with clean hands. If all pages are covered completely with lead white, wear gloves.” While books with hazardous illustrations are not dangerous when closed, there are varying levels of toxicity associated with different categories of books.

Archangel Michael Battling Devils; 2nd quarter 15th century, Belgium southeast and France northeast, parchment with ink, paint and gold, acquired by Henry Walters.
Archangel Michael Battling Devils, 2nd quarter 15th Century; Belgium southeast and France northeast, parchment with ink, paint and gold, acquired by Henry Walters. Courtesy of the Walters Art Museum

The conservation science focus of “If Books Could Kill” can be traced to the Walters Art Museum’s unique history. The Walters family and the museum have long been interested in technical research. The institution’s Conservation Department, the third of its kind in the U.S., was founded in 1934, and the museum’s science lab was established in 2004. There, conservation scientists work with items from the collection to answer questions of provenance, age and authenticity, with their findings shaping the content of exhibition labels for visitors.

An Illustrated Manuscript Confessory for the Use of a Deaf Youth, ca. 1819; watercolor and ink on paper, the Netherlands, The Waters Art Museum, museum purchase, 2023.
An Illustrated Manuscript Confessory for the Use of a Deaf Youth, ca. 1819; watercolor and ink on paper, the Netherlands, museum purchase, 2023. Courtesy of the Walters Art Museum

Dr. Herbert believes the recently opened book gallery is the museum’s “hidden gem. “It helps us realize the importance of the collection,” she says of the new exhibition space in the Medieval Gallery. The Walters’ manuscript collection is, indeed, important, with over 1,000 manuscripts from many cultures, 1,300 incunabula (printed books from before 1500) and 2,000 printed books from the 16th to the 20th Centuries.

“If Books Could Kill” offers a fresh perspective on historical bookmaking practices. It’s common to admire illustrated manuscripts’ beauty but less so to consider what went into it. The curators reassure us that it’s completely safe to view the toxic works in the show from afar and that there are ways for experts to handle these works safely. As the museum humorously notes on the placards: no curators, conservators or art handlers were harmed in the process of putting this exhibition together.

If Books Could Kill” is on view at the Walters Art Museum through August 3, 2025.

The Walters Art Museum Shines a Light On the Toxic History of Medieval Manuscripts