Abstract: A method of coating a substrate is disclosed. The method comprising the steps of that includes providing a substrate having a first surface, providing a particle based coating composition comprising particles, applying the coating composition to at least a part of the first surface of the substrate, and converting the particle based coating composition on the first surface of the substrate into a functional coating having a thickness of 50 nm to 25 ?mas measured along across section in a scanning electron microscope (SEM), wherein the particle based coating composition comprises nanoparticle, and converting the particle based coating composition involves a high intensity energy source heating at least a part of the coating composition, wherein the high intensity energy source is selected from the group of certain CO2 lasers and flame arrays. Furthermore an apparatus for preparing a coating is disclosed.