Toxic Bookcloth Colorants
Over 50% of the 19th-century, cloth-case bindings analyzed for this project to date contain lead in the bookcloth, across a range of colors. Analysis of a range of bookcloth colors has identified iron, copper, and zinc, which, while technically heavy metals by density, are generally considered not to be toxic. Analysis has also identified the following highly toxic heavy metals: arsenic, chromium, lead, and mercury.
Continue reading below for more information on books bound with arsenic-containing emerald green bookcloth.
Visit Chrome Yellow Bookcloth to learn more about bookcloth that contains chromium and lead. Bookcloths colored with ‘chrome yellow’ pigment may appear yellow, orange, brown, or a wide range of greens.
Arsenical ‘Emerald Green’ Bookcloth
In early 2019, analysis of 19th-century, cloth-case publishers’ bindings at Winterthur Library revealed bookcloth colored with “emerald green,” or copper acetoarsenite, an inorganic pigment known to be extremely toxic. This pigment’s popularity in England and the United States during the Victorian era is well documented. While the colorant was known to be widely used in textiles for home decoration and apparel, wallpaper, and toys, its use specifically in bookcloth had not been formally explored. Successful commercial bookcloths were a closely guarded trade secret during the nineteenth century, limiting our current understanding of their materiality and manufacture.
Conservation staff and interns at Winterthur Museum, Garden and Library conducted an initial survey of bookcloth pigments in the library’s circulating and rare book collections, later expanding their data set in cooperation with The Library Company of Philadelphia. Books published between 1837 and 1900, a time-period which aligns with the rising use of commercial bookcloth on publishers’ case bindings, were analyzed with X-ray fluorescence (XRF) spectroscopy. When arsenic and copper were detected together, Raman spectroscopy was used to confirm copper acetoarsenite.
The first 200 books tested represented a range of vivid bookcloth colors. Thereafter, only books covered in green cloth were selected for analysis, in order to focus on arsenic and move through the collection more efficiently. Now that analysis of green bindings is complete, other colors of bookcloth continue to be analyzed in stages.
Nearly 350 green cloth bindings in the collections of Winterthur and The Library Company of Philadelphia were analyzed. Two books procured from second-hand booksellers were also included in the testing, and were confirmed to contain emerald green. In total, 39 green cloth bindings were found to contain arsenic. Quantitative analysis performed at the University of Delaware Soil Testing Lab indicated that emerald green bookcloth colorant is extremely friable and offsets a significantly detectable amount of arsenic. Emerald green publishers’ bindings present a health risk to librarians, booksellers, collectors, and researchers, and should be identified, handled, and stored with caution.
Trends in Use of ‘Emerald Green’ in 19th-Century Bookbindings
Based on the data collected by project researchers and crowd-sourced data from other institutions, trends in the use of arsenical green pigment in 19th-century bookbindings have been identified. Arsenical green pigment has been confirmed in bookbinding cloth, paper book covers, endpapers, paper labels and onlays, leather onlays, and textblock edges. While further analysis has not always been possible to confirm the type of arsenical green pigment, in cases where further analysis was performed, the specific pigment has been identified as ’emerald green’ (copper acetoarsenite).
Composite image showing color variation of emerald green bookcloth on book spines, likely a result of air pollution. Even when the color on the spine has oxidized and browned, the green cloth on the front and back covers remains vividly green. Courtesy, Winterthur Library, Printed Book and Periodical Collection.
Bookcloth
- Primarily British and North American imprints
- Vibrant green bookcloth covering the boards (front and back covers)
- Vibrant green or faded brownish bookcloth on the spine
- Gold and blind stamped decoration, often paired with gilt textblock edges
- Publication dates primarily between 1840s-1860s
- Variations on a morocco grain pattern are common, although other embossed bookcloth grains have also been identified
Bookbinding Papers
Based on the data collected by project researchers, researchers at Northwestern University, and crowd-sourced data from other institutions, the following trends in the use of emerald green bookbinding papers have been identified:
- Primarily German, French, British, and North American imprints
- Color that ranges from minty to deep green
- Papers may be matte or glazed
- Papers may be plain or printed
- Publication dates range from 1816 to 1899*
*Note that the scope of this research focuses on 19th-century, mass-produced bookbindings. A precise date for when arsenical green pigment ceased to be used in bookbindings is impossible to pinpoint. However, with the rise of aniline dye production in the late 19th century, it is likely that heavy metal pigments fell out of use in bookbindings, as they did in many other manufactured goods, around the turn of the 20th century (c.1900).
French emerald green paper binding (1816). Courtesy of Ronald Smeltzer.
Identification Methods for Arsenic/Emerald Green Pigment
Emerald Green Color Swatch Bookmark
Analytical Methods for Identifying Arsenic/Emerald Green Pigment in Bookbindings