X-rays and wallpapers: the hunt for arsenic
I have been a heritage scientist at The National Archives for four and half years now. During this time I have identified materials, studied the condition of the collection, tested preservation methodologies, and advised on scientific matters. The evidence from these activities has impacted how we look after our collection whether it be how an adhesive is best removed from a paper or how best to clean the collection.
One of the projects that I have found most interesting involved the analysis of a series of wallpaper samples for the book, ‘Bitten by Witch Fever: Wallpaper and Arsenic in the Victorian Home’ by Lucinda Hawksley (Thames & Hudson Ltd, 2016). This book explores the history of the use of arsenic-containing compounds throughout the 19th century home, particularly in wallpapers, and the impact that this had on people’s health.
Wallpapers had become increasingly affordable due to the introduction of new manufacturing techniques and are reported to have often included arsenic compounds during this period, Scheele’s Green for example. Lucinda Hawksley contacted us to see whether we could substantiate these claims with scientific evidence.
Our collection includes a diverse series of wallpaper samples in its Board of Trade Design Registers. Designs often feature plants and animals in colour palettes ranging from the muted to the colourful and in sizes from the small and delicate through to the large and bold.
Designers and companies submitted these samples to the Board of Trade in order to copyright the designs. They were adhered onto the pages of large volumes with descriptions about when the designs were registered and by whom, recorded in a separate volume.
Over 200 samples, registered between 1879 and 1881, had been selected for us to analyse from the volume BT43/103 (Figure 1). The descriptions are available in the accompanying volume BT44/9. Thanks to a cataloguing project supported by volunteers and the Arts and Humanities Research Council, detailed descriptions are now available on Discovery, our catalogue.
We have our own portable X-ray Fluorescence (p-XRF) analyser. Out of our entire lab, this is my favourite piece of equipment because it can rapidly identify elements (for example, arsenic, iron, lead, tin). It was the perfect choice for indicating whether arsenic was present in the paints used on the wallpaper samples.
Analysis was complicated however due to the poor condition of the volume, its large size and heavy weight. We also needed to analyse the samples without removing them from the volume. By working closely with conservators I developed a method of p-XRF analysis that was safe to use on the wallpaper samples and volume yet gave the results we needed in the short time available. This included developing a supporting structure on which to place the opened volume and placing polyester between the design and the page to which it was adhered.
I took over 430 measurements from various colours within 279 wallpaper samples; over 164 of these samples were likely to contain arsenic. While arsenic is often associated with green shades in wallpapers I found that some green shades did not contain it, while some shades of cream, yellow, and brown did.
Despite arsenic being present in some wallpaper samples, the quantities are very low and with limited exposure, controlled environmental conditions and careful handling, they do not pose a health risk to readers.
Working on this project was a great learning experience for me and gave me the opportunity to work with what I feel are some of the most fascinating and beautiful records within our extensive collection. I’ve definitely been bitten by the XRF bug and look forward to the next opportunity use our p-XRF analyser to enhance our understanding of the collection.