Arsenic found In Bonad Paintings
One of the naturally occurring substances is arsenic that occurs in several forms and most often in compounds with other chemical elements. It is known to be extremely poisonous and has numerous industrial applications.
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Recently, this toxic substance was found in the traditional Swedish bonad paintings. This discovery was made by Ingalill Nystrom, paintings conservator and conservation scientistat the University of Gothenburg, Sweden.
Ingalill Nystrom analyzed the paints and techniques used in the traditional painted wall hangings from southern Sweden.
Bonads were painted by itinerant artists. Themes of these paintings were often chosen to commemorate a family milestone. These painted wall hangings tell a story, often with a biblical theme, and were put up in farmhouses on special occasions.
"It's important to know about the materials used in these wall-hangings so that we can preserve them," said Nyström. "We need to know whether they run the risk of being bleached or broken down by different kinds of exposure, treatment or conservation method. It's also important for the people who handle them to know whether any of the substances in them could be harmful or toxic."
Apart from arsenic the other toxic pigments found in these wall hangings were orpiment and emerald green which contain arsenic. Orpiment was commonly found in yellow pigment in the wall hangings throughout the 18th century and well into the 19th century too. Emerald green appears in some 19th century wall hangings.
"So it's important to be careful when handling them. Several of the pigments and dyes are also sensitive to light, and the binding agent in the hangings is sensitive to damp and moisture."
This thesis is the first of its kind. Till date, the studies into bonad painting have always originated in the humanities, from an art/cultural history perspective.
The aim of the study was to investigate the technology, materials and painting techniques used in the wall hangings.
"The quality and characteristics of the materials used can play a role in both these paintings' technical opportunities and their limitations. In my book I describe the various raw materials, approaches, potential painting tools and other aids that could have been used," says Ingalill Nystrom.
The study also discusses the number of paints that may have been mixed and applied to the wall hangings.
This thesis is a cross-disciplinary study that combines art technological source research with spectroscopic analysis methods.
For the study, she examined more than 70 bonad paintings originating from southern Sweden between 1700 and 1870, and also 700 paint samples.
The materials used often comprised paint made with cheap pigments mixed up with egg and sometimes a touch of flour. The paint was generally applied to recycled linen primed with flour glue. Typically, templates were used for the figures in the scenes depicted.