A coating apparatus includes modular interfaces and substrate receptors for accommodating various shapes and sizes of monolith substrates when coating layers are applied onto the monolith substrates. The monolith substrates are laterally surrounded by an elastically deformable sleeve that prevents lateral leakage of a vacuum out of the monolith substrate when a vacuum is applied to opposing ends of the monolith substrate, thereby eliminating needs for bulky vacuum chambers. The coating apparatus also includes valves and control apparatus that enable excess precursor liquid to be drained from monolith channels in-situ, without the use of additional spin-drying steps. Coating methods for using the coating apparatus are provided.