The conservational heritage of wall paintings and buildings : an FT‐Raman spectroscopic study of prehistoric, Roman, mediaeval and Renaissance lime substrates and mortars

Raman spectroscopic studies of ancient lime-based plasters and mortars from periods ranging from prehistoric through Roman to mediaeval have revealed the potential application of the technique for the non-destructive analysis of these ubiquitous substrates that are found in constructional and decorative work. Characteristic information obtained from the Raman spectra of these materials obtained with near infrared excitation at 1064 nm provides an insight into ancient technological practices and particularly the methodology of application of the associated pigments in wet fresco techniques in the transition towards gypsum plasters. The assignment of molecular features to the plasters and to their reaction product with moist air, calcium carbonate, facilitates the assessment of the extent of curing of the material that has taken place and is relevant to the conservation of buildings and fresco art works. Copyright © 2008 John Wiley & Sons, Ltd.