Abstract: Some variations provide an emulsion-colloid system for forming a colloidal barrier material disposed on a substrate, the system comprising a hydrophilic first liquid, an acid, a gelling agent, a hydrophobic second liquid, a plasticizer, and optionally additives, wherein the emulsion-colloid system is characterized by (1) a first instance that is a flowable emulsion above 60° C. and less than the boiling point of the first liquid, and (2) a second instance that is a colloid below 40° C. The emulsion-colloid system is capable of reversible transition, mediated by temperature, between the first instance and the second instance. The disclosed colloidal barrier material provides the functionality of plastic alternatives while removing disadvantages. The disclosed colloidal barrier material reduces labor-intensive application of the barrier, such as the case for covering grain piles with plastic tarps.