A granular molding material with a binder comprising a phenol novolac and a polyisocyanate which hardens upon addition of amine catalysts wherein the molar ratio of phenol to formaldehyde in the novolac is 1:0.25 to 1:0.5 and has the formula ##STR1## wherein R, R' and R" are individually selected from the group consisting of hydrogen, alkyl of 1 to 12 carbon atoms, hydroxy, cycloalkyl of 3 to 12 carbon atoms and an anellated ring and X is an integer from 0 to 4 or >4 with the percent molar distribution based on X is as follows:______________________________________ when X = 0: 20-55% X = 1: 15-30% X = 2: 10-30% X = 3: 0-50% X .gtoreq. 4: 0-2.5% ______________________________________ for the production of improved foundry cores and molds.