Inadvertent or unavoidable contact of an acid with an acid-reactive substance may preclude the acid's use in another location where its reactivity is more desired. Excessive reactivity of acids toward acid-reactive substances may lead to undesired effects such as surface erosion, matrix deconsolidation, scaling, and the like. Methods for protecting an acid-reactive surface from excessive reaction may comprise: depositing a protective coating comprising an N-(phosphonoalkyl)iminodiacetic acid or any salt thereof onto an acid-reactive surface; and contacting a mineral acid or an organic acid with the protective coating without substantially reacting the acid-reactive surface.