Abstract: This invention relates to a low-viscosity two-component unfilled polyurethane adhesive having a urethane content of from 10 to 18 percent by weight, based on the weight of nonfilled polyurethane polymer, based on(a) a low-viscosity isocyanate component comprising an organic polyisocyanate in a quantity sufficient to provide an isocyanate index of about 100 to about 150; and(b) a low-viscosity phase-stable curative component comprising(i) 5 to 50 equivalent percent of a polyether polyol and/or a polyether terminated by aromatic amino groups having an equivalent weight greater than 500,(ii) 30 to 95 equivalent percent of 2-methyl-1,3-propanediol, and(iii) 0 to 35 equivalent percent of a chain extender and/or crosslinker other than 2-methyl-1,3-propanediol, with the proviso that the equivalent ratio of component (b)(iii) to component (b)(ii) is no more than about 0.6.