A Mid-IR Photoacoustic point spectroscopy sensor providing in-depth chemical information of CH artefacts with high molecular specificity and identifying organic or inorganic compounds linked to degradation of CH materials such as varnish, paint, glue, wood, metal, glass, stones. The Mid-IR system will be adapted to a transportable system to support complementary NLOM spot measurements enabling to extract complementary chemical information from the same region via the employment of the two techniques.