Scoop 1.1945 Technical Analysis

Length 49 cm, Width 21 cm, Depth 11 cm

Infra-red Imaging

The infra-red (IR) images of scoop 1.1945 shown above, highlight a pattern of abrasions on the interior surface of the object. Could these abrasions give some indication as to how the object was used?

Wood Species Identification

While this object is identified as being made from Alder (Scannell, 1980), the method of identification is unclear. A small sample of wood was collected from scoop 1.1945 to confirm the prior wood identification. 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. 

The series of micro-features identified in the SEM images above indicate that this object is made from Alder (Alnus glutinosa) wood. 

FTIR spectral analysis showing comparison of sample collected from scoop 1.1945 (blue), reference sample for Birch ( Betula pendula ) (red), and reference sample for kerosene (green) 

FTIR spectral analysis showing comparison of sample collected from scoop 1.1945 (blue), reference sample for Birch (Betula pendula) (red), and reference sample for kerosene (green) 

FTIR Analysis

The sample of wood collected from scoop 1.1945 was analysed using Fourier Transform Infrared Spectroscopy (FTIR). The spectral analysis above compares the sample from scoop 1.1945 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 1.1945 corresponds closely with that for Birch (Betula pendula) wood, there are a number of additional peaks present in the wood sample spectrum for scoop 1.1945. 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. 

Bibliography

Scannell, M. (1980) Report on wooden trays, methers and other objects from Armagh Museum. Dublin: Department of Agriculture and Fisheries, Ireland.