Artistic yellow pigments, commonly employed from antiquity, were investigated by morphological, spectrophotometric and compositional analyses. Namely, scanning electron microscopy-energy dispersive X-ray (SEM/EDX) characterisations and reflectance, attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and Raman spectroscopy were carried out on egg yolk tempera models to discriminate the pigments. The models were irradiated with excimer KrF (248 nm) laser at different working conditions, and the effects induced on colour were related to chemical and physical modifications through the same analyses, as a function of laser parameters.It came out that the effects on the pictorial layers are always related to the modifications of the binding medium and, in addition, the laser radiation induces dehydration and transformation of iron oxides in natural earths.