NOVELTY - Reducing the formation of visible defects in a surface of a coating composition on a substrate, comprises: coating a curable composition containing a solvent onto a surface of a substrate, removing the solvent from the coated curable composition to form a dried curable coating, and heating the dried curable coating to a temperature at which the curable coating exhibits leveling flow; or coating a solventless curable composition onto a surface of a substrate to form a curable coating and heating the curable coating to a temperature at which the coating exhibits leveling flow.    USE - The method is useful for reducing visible defects, such as mottle, in coatings. The method is useful to make coated substrates for use in optical articles without a matte finish, which is gain diffusers and brightness enhancement films; abrasive articles; graphics articles; medical articles; sensors; component articles for fuel cells; photographic articles; and medical imaging articles.    ADVANTAGE - The gas flow is minimized on the coated side of the substrate and/or the temperature of the coating on the substrate is kept low enough, that is, the viscosity of the curable coating is high enough, to prevent new coating defects, e.g. mottle, from forming prior to, or during the curing process. Dewetting is reduced via surface treatment of the surface of the web or substrate to increase its surface energy.    DETAILED DESCRIPTION - Method for reducing the formation of visible defects in a surface of a coating composition on a substrate, comprises: either coating a curable composition containing a solvent onto a surface of a substrate, removing the solvent from the coated curable composition to form a dried curable coating, and heating the dried curable coating to a temperature at which the curable coating exhibits leveling flow; or coating a substantially solventless curable composition onto a surface of a substrate to form a curable coating, where the surface of the curable coating has visible defects, and heating the curable coating to a temperature at which the coating exhibits leveling flow, where the surface of the coating has reduced visible defects.    DESCRIPTION OF DRAWING(S) - The figure shows a depiction of a substrate coating process that involves the method for reducing the formation of visible defects in a surface of a coating composition on a substrate.    Coating process (200)    Substrate unwinder (202)    Coating apparatus (204)    Gap dryer (206)    Zoned drying gas oven. (208)