Raman microspectroscopy interrogating 19th and 20th century painted trades union banners

Description/Abstract

We have previously developed protocols for the application of Raman microspectroscopy to studies on painted
textiles. We have further assessed the value of such microanalyses in the identification of both inorganic and organic
constituents, including original components and consolidants used in conservation treatments.

This paper presents the
results of a recent study on a number of 19th- and 20th-century trades union banners directed at collating a spectral database
of inorganic pigments used in the illustrations and at probing the preparative process prior to painting. Such information
will contribute to an understanding of the manufacture of such banners and their current condition, leading to the development
of optimum conservation procedures.

While Raman spectroscopy has the potential to be used in situ and, with the appropriate protocol, is non-destructive,
nonetheless we have found that the analysis of resin-embedded cross-sections is to be preferred with microtoming providing
the cleanest sample surface. The optimum methodology for acquiring good quality Raman spectra is described including
operation in the confocal mode, with consideration of fluorescence, interference from resin, laser-induced photochemistry,
and so on.