Abstract: The present disclosure is directed to a two-part coating composition, wherein the two-part coating composition comprises: Part A comprising (a) a polyol component comprising at least one of a difunctional polyol, a trifunctional polyol, and a tetra functional polyol; (b) a foam catalyst; (c) optionally, a gel catalyst; and (d) water; and Part B comprising an isocyanate functional material, wherein the isocyanate functionality is at least 2, preferably an isocyanate prepolymer with a functionality of greater than 2 and less than 3. The coating composition produced an expanded closed-cell foam coating that provides protection for electronic substrates operating in harsh environments.