A method includes coating a substrate to provide a flame resistant substrate. In an embodiment, the method includes exposing the substrate to a cationic solution to produce a cationic layer deposited on the substrate. The cationic solution comprises cationic materials. The cationic materials comprise a polymer, a colloidal particle, a nanoparticle, a nitrogen-rich molecule, a geopolymer, a carbon-based filler, or any combinations thereof. The method also includes agitating the substrate. The method further includes exposing the cationic layer to an anionic solution to produce an anionic layer deposited on the cationic layer to produce a layer comprising the anionic layer and the cationic layer. The anionic solution comprises a layerable material.