Non - intrusive thermal measurement methods adapted to painted cave walls

Abstract

Painted caves such as Lascaux are highly sensitive to their surrounding atmospheric conditions. To preserve them for the upcoming generations, it is necessary to understand thermal and mass transfers that happened between the painted walls and the air. A cave has been monitored with an infrared camera and a Peltier sensor. The singular value decomposition has been first applied to extract the relevant information. It revealed a non-random thermal behavior of the wall. Then a semi-infinite model combined with a Fourier analysis led us to evaluate the thermal effusivity of the cave wall. This latter is subjected to large measurement uncertainties.