Pigments and binders are known to influence drying and ageing mechanisms of paint films. However, the study of the long-term mechanical behaviour of paint films and its relationship with paint degradation and conservation still needs further investigation. This paper presents an insight into the role of cobalt blue pigment in the mechanical properties of some modern paint films by studying selected commercial oil and alkyd paint films containing cobalt blue. In addition, several representative mock-ups containing cobalt blue mixed with drying and semi-drying oils and some common additives were also tested for comparison purposes. Optical microscopy, SEM-EDX, XRF, VIS-reflectance spectroscopy, FTIR-ATR and GC-MS analysis were carried out to identify pigments, binders, additives and fillers. Uniaxial tensile measurements were run to test the mechanical performance of the studied paint films. The differences in the mechanical behaviour led to the evaluation of the discrepancies found in the chemical and physical properties of the different formulations studied.