The present invention provides a water-based coating and/or coating system that can be used to form sag resistant wet layers or coatings on a wide range of substrates. The coating system is particularly effective for protecting metal-containing substrates, such as intermodal cargo containers, against corrosion. As an overview, the present invention provides water-based compositions suitable to form primer coats on substrates. Desirably, the primer incorporates a high level of one or more CAS agents for excellent sag resistance while drying in a broad range of relative humidity environments. Alternatively, modifications can be made to control temperature and humidity during spray application and drying as a way to increase sag resistance of the coating.