The present invention provides compositions for and methods of rapidly making roof coatings, wherein two-component aqueous compositions comprise a component one that has a pH of from 7.5 to 10 (i) one or more emulsion copolymers having a glass transition temperature (Tg) as determined by differential scanning calorimetry (DSC) of from −45° C. to 0° C., and (ii) one or more anionic surfactants, and, in a separate component, (iii) an aqueous acid chosen from a (poly)carboxylic acid or polymeric polyacid. The compositions have little or no ammonia, set within 10 minutes, preferably, a minute or less, and allow one to apply a film as thick as from 0.3 to 3 mm in a single application by co-spraying the two-components or applying them sequentially in one or several passes over a roofing substrate.
