Polarization Second Harmonic Generation Discriminates Between Fresh and Aged Starch-Based Adhesives Used in Cultural Heritage.
In this work, we report that polarization second harmonic generation (PSHG) microscopy, commonly used in biomedical imaging, can quantitatively discriminate naturally aged from fresh starch-based glues used for conservation or restoration of paintings, works of art on paper, and books. Several samples of fresh and aged (7 years) flour and starch pastes were investigated by use of PSHG. In these types of adhesives, widely used in cultural heritage conservation, second harmonic generation (SHG) contrast originates primarily from the starch granules. It was found that in aged glues, the starch SHG effective orientation (SHG angle, θ) shifts to significantly higher values in comparison to the fresh granules. This shift is attributed to the different degree of granule hydration between fresh and aged adhesives. Thus noninvasive high-resolution nonlinear scattering can be employed to detect and quantify the degree of deterioration of restoration adhesives and to provide guidance toward future conservation treatments.
1Institute of Electronic Structure and Laser (IESL),Foundation for Research and Technology Hellas (FORTH),100 N. Plastira Street,71110 Heraklion,Crete,Greece.
Sotiris
S
Psilodimitrakopoulos
1Institute of Electronic Structure and Laser (IESL),Foundation for Research and Technology Hellas (FORTH),100 N. Plastira Street,71110 Heraklion,Crete,Greece.
Evaggelia
E
Gavgiotaki
1Institute of Electronic Structure and Laser (IESL),Foundation for Research and Technology Hellas (FORTH),100 N. Plastira Street,71110 Heraklion,Crete,Greece.
Kristallia
K
Melessanaki
1Institute of Electronic Structure and Laser (IESL),Foundation for Research and Technology Hellas (FORTH),100 N. Plastira Street,71110 Heraklion,Crete,Greece.
Vassilis
V
Tsafas
1Institute of Electronic Structure and Laser (IESL),Foundation for Research and Technology Hellas (FORTH),100 N. Plastira Street,71110 Heraklion,Crete,Greece.
George
G
Filippidis
conservation-restoration; cultural heritage; nonlinear microscopy; polarization second harmonic generation; starch-based adhesives