Losset 1887.1 Technical Analysis

Length 91.5 cm, Width 52.5, Depth 8.7

Multi Spectral Imaging

The ultra-violet (UV) images shown above highlight the presence of adhesive on the object. The hessian patch on this object was likely applied as a preservative measure some time after the objects discovery. The adhesive used to apply the patch fluoresces under UV light ,and the images above indicate the extent to which the adhesive extends onto the object surface beyond the edges of the patch. While collecting analytical samples from areas of existing damage or deterioration can lessen the visual impact on an object, this region was deliberately avoided for object sampling due to the post-collection treatment visible in the UV images..  

Wood Identification

A small sample of wood was collected from the underside of losset 1887.1  (see annotation 1 on the model above). This losset was carved from a large tree trunk, with the long axis of the object aligned with the longitudinal axis of the tree.  Given the orientation of the object in relation to the tree trunk from which it is formed, the sample was collected from a region of wood that contains some of the 'newest' growth rings available for this object. In addition, as the sample location corresponds with deteriorated wood on the underside of the object, collecting the sample from this region has minimised the visual disruption to the object. 

A sub-sample was cut into thin slices known as 'sections', and mounted for examination using a scanning electron microscope (SEM). The scanning electron microscope can resolve microscopic features in the wood that  help to identify the particular species of tree that the losset was made from. The combination of features described in the images above indicate that this object is made from Birch (Betula pendula) wood. 

 

FTIR spectral analysis showing comparison of sample collected from losset 1938.9734 (dark blue), reference sample for Birch ( Betula pendula ) (red), and reference sample for kerosene (blue) 

FTIR spectral analysis showing comparison of sample collected from losset 1938.9734 (dark blue), reference sample for Birch (Betula pendula) (red), and reference sample for kerosene (blue) 

FTIR Analysis

The sample of wood collected from losset 1887.1 was analysed using Fourier Transform Infrared Spectroscopy (FTIR). The spectral analysis above compares the sample from losset 1887.1 with a reference sample for European Birch (Betula pendula) wood . As the predominant component of plant fibres is cellulose, and other major constituents (hemicelluloses and pectins) are also polysaccharides, the FTIR spectra of different cellulosic plant materials are superficially similar and cannot be readily distinguished by eye. In addition, degradation of one or more components of the plant material e.g. through oxidation of the cellulose molecule, will influence the position and intensity of spectral peaks relative to non-deteriorated reference spectra.

There are, however, a number of fairly consistent spectral peaks indicative of cellulosic carbohydrate within a sample. The majority of cellulosic carbohydrates will exhibit a broad band from 3600–3100cm-1 arising from O-H stretching in bound or absorbed water. A broad band relating to C-H stretching from aromatic hydrocarbons at 3100-3300 cm-1 can be obscured or partially obscured by the broad O-H stretching band described previously. Additional peaks relating to the cellulose component of plant material include peaks for C-H stretching of methylene groups between 3000 and 2800cm-1, C-H deformation in cellulose and hemicellulose at 1371cm-1, C-H vibrations at 1319 cm-1, an intense peak at about 1030cm-1 relating to C-O bonding (this is typically a combined peak for cellulose and hemi-cellulose), and a shoulder at 897cm-1 relating to C-H bending. Additional shoulders at 1155cm-1 and 1105cm-1 on the C-O band at about 1030cm-1 relate to stretching and contraction (so called ‘breathing’) vibrations within the benzene rings, and glycosidic linkages between carbohydrate molecules respectively.

While the spectrum for 1969.678 corresponds closely with that for Birch (Betula pendula) wood, there are a number of additional peaks present in the wood sample spectrum for losset 1887.1. The strong peaks visible between 3000 and 2800 cm-1 and between 1480 and 1300 cm-1 relate to C-H stretching, and are consistent with petrochemicals- hydrocarbons derived from crude oil.  The presence of a petrochemicals on this object most likely relates to the use of petroleum derived wood boring insect treatments, commonly applied to objects in museums throughout the 19th and 20th centuries.  The blue reference spectrum for kerosene is shown here as a generic petrochemical example for comparison.