In the coatings industry, colour matching is a fundamental process that has traditionally been carried out on paint in its hardened state. The subtle adjustments required for product control or during colour development are thus time- and cost-intensive steps, which can be significantly accelerated by measuring the colour of the liquid paint. However, this approach presents a considerable challenge: a paint undergoes significant colour shifts during drying, due to a complex interplay of chemical and physical processes, such as changes in the refractive index and the loss of ligands in certain pigments [1]. The reflection spectra shown in Figure 1 ...