Disclosed are methods for coating a substrate. These methods include: (a) vertically orienting the substrate between a vertically oriented backstop and a spray gun; (b) at least partially coating the vertically oriented substrate with a substantially 100% solids, radiation curable liquid coating composition by passing the composition through the spray gun wherein the composition is atomized; whereby a portion of the atomized coating composition deposits on the vertically oriented substrate and a portion of the atomized coating composition deposits on the vertically oriented backstop; (c) exposing the coated substrate to ionizing radiation and/or actinic radiation to cure the coating composition deposited thereon; and (d) removing and reusing at least a portion of the coating composition deposited on the vertically oriented backstop. Related coating systems are also disclosed.