Objectives

Surveying :

Survey to serve as a reference to assess frequency and type of deterioration found in collections and, also to rank degradation level of polymer. It will allow to assess the spread of the degradation in collections after 10 years of natural ageing.

Monitoring :

The main objective is the non-invasive spectroscopic characterisation of plastic-based objects during and after ageing. The insertion of optical fibres in situ will allow a continuous monitoring of the visible and NIR in order to give prompt information about the photoreaction rate and the impact of the environment.

Work description

Task 1 : Survey of collections for identification and preservation condition

Partners will establish a survey form that will serve to establish a survey of plastic objects collections in order to assess the most common visible deterioration problems found in these collections. Distortion, cracks, smell, colour changes, corrosion product, deposit (...) will be noticed. This survey should help determine further priority and example for analysis of degradation product and for cleaning. It will serve as a reference to assess frequency and deterioration found in collections. This will also allow ranking degradation level of polymer objects and establishing typology of objects and their deteriorations.

Based on a survey form, conservators will investigate collections of polymeric based objects in order to assess the most common visible deterioration problems found in these collections. Distortion, cracks, smell, colour changes; corrosion products and deposits will be noticed and sampled, if possible, for further analysis in the lab. Some interesting analytical tools, depending on their availability and portability, will be tested in the field to find out how well it would function on site. Three museum collections are selected and plastic objects will be analyzed. Data will be collected not only from different plastics, but also from non-synthetic materials often imitated by, and easily mistaken for, plastics, such as tortoise shell and horn.

Task 2 : Monitoring changes of synthetic plastic artefacts in museum collections

When all partners have selected the most suitable plastic objects in the collections, we shall record reflectance spectra of the laboratory samples before ageing in the entire range 0.380 µm – 11.0 µm using spectrometers equipped with optical fibres. Then, we shall take multispectral images of the same samples in the visible and near-IR range (0.40 – 1.8 µm). The images will be processed to provide evidence on possible non-homogeneity. All the above data will constitute the background for a later investigation.

During natural ageing, the artefact will be investigated using the same procedure and instrumentation and the results will be compared with those obtained from the original samples. An attempt will be made to identify possible alteration products and their distribution on the samples. Evaluation of changes by chemiluminescence measurements will be applied to some reference objects. Specific plastic artefacts may be prepared and exhibited in a museum environment for such purpose.