Topical sealants are effective by coating substrates, making an FR barrier between the substrate and the source of ignition, such as with back-painting scenery. Since the substrate itself may not have been previously treated and will remain untreated throughout, some fire marshals may not accept topical treatment for temporary decorative and scenic materials, although most do. Topical treatments alone are almost never acceptable by building code for permanent construction materials.
Paint Additives will not change the opacity or color of paint and sealants or change the coverage, they are ideal for non-porous substrates, untreated wood products, or previously painted scenery. Add to clear acrylic glaze to create an FR sealant. Each yields a "Class A" or "I" rating to your coating.
NOTE: Longevity of any FR additive depends on the use of the treated fabric (and how much it is handled) and the environment (mostly humidity and environmental changes) in which the treated fabric lives. It also depends on whether the treated fabric is clean or has been accumulating dust (stage dust, shop dust) and/or air-borne oil particles (from a restaurant or cafeteria kitchen).