The present invention relates to a dry state process for coating a substrate, said process comprising the steps of: (A) forming a mixture comprising: (i) particles of a coating material; and (ii) particles of a substrate; wherein the substrate, or at least a portion thereof; and/or the coating material, or at least a portion thereof; is capable of undergoing a glass transition; and (B) sintering the mixture formed in step (A) at a temperature greater or equal to the glass transition temperature of the substrate, or portion thereof, or the coating material, or portion thereof, that is capable of undergoing a glass transition, so as to form a coated substrate.