Abstract

The characterization of the drying process of paints and coatings on the surfaces is important for many industrial applications. We present a new optical method to study the drying process of varnish based on immersion solid matching technique. The principle of the method is to match the refractive index of dry varnish with the added particles, making the dried varnish optically transparent. The state of the drying process can be evaluated by following the transparency of the varnish by visual inspection or imaging by camera. The method has several merits since it is non-contact, fast, simple and low-cost. In addition, particles that are invisible in dry varnish can provide improved properties such as hardness, abrasion and corrosion resistance or retard flammability without sacrificing the optical appearance of the coating.