Trough 473.1932 Technical Analysis
Length 48 cm , Width 26.5 cm, Depth 14.4 cm
The infra-red images above highlight dark marks on the interior surface of trough 473.1932. The darks areas appear to be scorch marks, suggesting that this vessel may have been used for hot stone cooking. In this technique stones heated in a nearby fire are added to a liquid within the vessel. The stones are continually retrieved, reheated, and returned to the liquid until it reaches the desired temperature.
Wood Species Identification
A small sample of wood was collected from trough 473.1931. A small amount of the sample was cut into thin slices known as 'sections', and these were mounted for examination using a scanning electron microscope (SEM). The scanning electron microscope allows us to resolve microscopic features in the wood that can help identify the particular species of tree that the spade was made from. Unfortunately the wood sample collected from this object was badly deteriorated. The images above, showing the wood in cross-section do not indicate the tree species from which the object was made.
The sample of wood collected from trough 473.1932 was analysed using Fourier Transform Infrared Spectroscopy (FTIR). The spectral analysis above compares the sample from trough 473.1932 with a reference sample for European Birch wood (Betula pendula), and a reference sample for natural gypsum.
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.
(add section here indicating additional/complimentary cellulosic peaks from papyrus [included as a generic cellulosic material])