Abstract: The present invention relates to a coating composition comprising a system comprising a dye encapsulated in a matrix of a polymer, wherein the dye only shows absorption in a non-visible part of the light spectrum, wherein the encapsulated system is able to undergo a detectable change in the absorption properties under the influence of moisture. The invention further describes a method to detect moisture in objects, the method comprising the steps of (a) providing an object with a signalling layer, said signalling layer showing light absorption in a non-visible part of the light spectrum and a change in this light absorption under the influence of moisture, and (b) measuring the light absorption or reflectance of the coated object in the non-visible part of the light spectrum.