Sol-gel silica coatings for the protection of cultural heritage glass

To slow down the phenomenon of weathering of ancient stained glass, the present work proposes the coating of glass. Several recipes have been tested in the past. The coatings are made of sol-gel silica prepared with different catalysts like H⁺, Pb(II), Sn(IV) and without catalyst. All the investigated samples show a good adhesion of the coating to the glasses used to simulate the behaviour of ancient artefacts and a good resistance to ageing tests.In the present work, some tests on Au and Ti surfaces coated with sol-gel silica were done, in order to investigate the adhesion of a H⁺ sol-gel coating to the surface of metals. In fact, in the case of glassy mosaics called “golden leaf tessera”, the adhesion of the glass to the metal is a critical point, due to the fact that the weathering of such tesserae causes the detaching of the “cartellina” (small glass layer) from the metal leaf. The main techniques adopted to investigate are optical microscopy (OM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and Rutherford backscattering spectroscopy (RBS).