Investigation of Commercially Available Rabbit Skin Glues Using MALDI-TOF MS 

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Rabbit skin glue is often indicated as a preferred binder for the preparatory layers in traditional water gilding and as a treatment material in gilded objects conservation and restoration. Previous studies, however, have suggested that references to this material are mostly absent from pre-twentieth-century recipes, treatises, and literature and that some modern preparations sold as "rabbit skin glue" may in fact be generic animal collagen glues.

 

In this study, thirteen commercially available or commercially purchased products sold as "rabbit skin glue" were analyzed by peptide mass fingerprinting (PMF) with matrix-assisted LASER desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) in order to characterize their proteins and suggest a species- or family-specific animal source. 

 

Five of the products analyzed had protein fingerprints consistent with cattle, with no indication of any protein mixture; three of the products analyzed had protein fingerprints consistent with rabbit, with no indication of a mixture; and five of the products had a protein fingerprint consistent with a mixture of proteins, either cattle protein and rabbit protein, or cattle protein and another undetermined animal protein.

 

This study provides scientific results that prove that some of these materials’ compositions are not consistent with their advertised or implied compositions; this study can therefore be referenced by future researchers or users of these products to inform their work. 

 

This project continues research begun during Spring 2020 at the Winterthur/University of Delaware Program in Art Conservation. Samples were prepared by Catherine Matsen, Dr. Dan Kirby, Dr. Rosie Grayburn, Lara Kaplan, Sarah Towers, and Kate Acuna at Winterthur Museum. MALDI-TOF Mass Spectrometry was performed by Dr. Papa Nii Asare-Okai and Rosie Grayburn at the University of Delaware. Data was interpreted in consultation with Catherine Matsen, Dr. Kate Duffy, and Dr. Dan Kirby.

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View analytical report HERE