Degradation of Lime Wood Painting Supports

Degradation of wood, being a natural process, leads to destruction of wooden objects of historic and cultural value, resulting in loss of cultural heritage. Wood can survive centuries or even thousands of years, if kept in an environment, which limits microbial activity. In an unfavourable environment physical, chemical and morphological modifications of wood also take place as a result of biodegradation. It is important to know the type of degradation and how the processes influence material properties if wooden items are to be properly preserved. The objective of this study is to present new knowledge on noninvasive techniques useful to assess the preservation status of lime wood in art objects. The methods of investigation were optical and electronic microscopy, wide angle X-ray scattering (WAXS), and FT-IR spectroscopy. Following a deconvolution process of the diffraction patterns, crystalline index, apparent lateral crystallite size, proportion of crystallite interior chains, orientation index, mesomorphism, cellulose fraction have been determined and shown to change with increasing age of painting supports. Structural modifications were assessed by FT-IR spectrometry and 2D correlation FT-IR spectroscopy, while morphological modification were characterised using SEM. The principal hetero-elements of the lime wood samples were detected by EDX. It can be concluded that only a multi-analytical approach can provide the information needed on wood degradation processes.