ON THE FEASIBILITY OF DATING PORTABLE PAINTINGS: PRELIMINARY LUMINESCENCE MEASUREMENTS ON GROUND LAYER MATERIALS

Abstract

A typical oil painting stratigraphy consists of the canvas substrate, the ground layer, the layer of paint and eventually the varnish layer. The ground layer, a mixture of inorganic and organic material could be a very helpful tool for indirect dating. The present study presents preliminary luminescence measurements on the main inorganic constituents of the ground layers for paintings between the 15th and the 20th century. Eight different substances were selected, based on the most common materials applied throughout these centuries. Most among the materials subjected to the present study present TL glow curve with different, unique shape. Notable exceptions stand in the case of the most recently invented materials such as zinc white, titanium white and lead white. Towards direct dating purposes, a number of luminescence features, such as sensitivity, sensitization after repeated cycles of irradiation-measurement, bleaching ability as well as thermal stability were studied for both cases of TL as well as OSL. Preliminary results indicate that kaolinite and gypsum stand as very promising candidates towards luminescence dating of portable paintings. Further work is required in order to establish their usefulness.