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Resins obtained from Pinus genus species have been widely used in very different fields throughout history. As soon as they are secreted molecular changes start altering their chemical, mechanical and optical properties. The ageing processes are complex and chemical and structural changes associated to resin degradation are not yet fully known. Many questions still remain open, for instance changes happening in pimaranes, one of the two diterpenoid constituents of the resin.A systematic study of the ageing process of Pinus resins is done through of Fourier Transform Infrared Spectroscopy (FTIR) using chemical standards and complementing obtained results with Gas Chromatography coupled to Mass Spectrometry (GC/MS) analysis when necessary. Moreover, long-term degradation processes are also investigated through the analysis of a selection of dated historical resins. The study overcomes the limitations of GC/MS and brings new information about the reactions and interactions between molecules during Pinus resin ageing process, providing information about bonds affected and unaffected and can be used as specific markers of the degradation and of the resins themselves.

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Synchrotron radiation Fourier transform infrared (SR-FT-IR) microspectroscopy represents an advance over conventional FT-IR spectroscopy because it gives a higher signal/noise ratio at the highest spatial resolution due to the high brightness and collimation of synchrotron radiation. It has been successfully applied to the study of ancient paintings, alteration and corrosion layers which are heterogeneous microlayered materials made by complex mixtures of organic and inorganic compounds. Moreover, the high brightness attribute allows FT-IR spectra to be routinely obtained directly on the surfaces of the objects and opens the possibility for nondestructive testing of museum objects. We present in this paper a selection of applications of SR-FT-IR to the analysis of ancient paintings, alteration and corrosion layers where the technique has proven to be especially useful: first, the separation and identification of pigment microparticles from ancient Roman wall paintings; second, the determination of the binding media and the byproducts resulting from the interaction between binders and pigments from medieval altarpieces; and third, the study of the surface corrosion layers of a bronze helmet by means of direct analysis of the surface.