The present invention is directed to a method for coating a substrate comprising: (a) applying a caustic cleaner onto at least a portion of the substrate; (b) rinsing at least a portion of the substrate that was subjected to step (a) with water; (c) applying an acid cleaner onto at least a portion of the caustically cleaned substrate; (d) rinsing at least a portion of the substrate that was subjected to step (c) with water; and (e) applying a conversion coating comprising zirconium onto at least a portion of the acid cleaned substrate; and wherein at least one of the materials used in steps (c) and (e) is substantially chrome free. The present invention is also directed to a substrate, such as an aluminum substrate, that has been coated using the aforementioned method.