a foundry moulding composition comprising a granular refractory material , and from 0 . 5 % to 8 % based on the weight of the refractory material of a binder comprising an aqueous solution of a potassium alkali phenol - formaldehyde resin , said aqueous solution having a solids content of from 50 % to 75 % and said resin having a weight average molecular weight of from 600 to 1500 , a formaldehyde : phenol molar ratio of from 1 . 2 : 1 to 2 . 6 : 1 and a potassium hydroxide : phenol molar ratio of from 0 . 2 : 1 to 1 . 2 : 1 and at least one silane in an amount of from 0 . 05 % to 3 % based on the weight of said aqueous solution , said binder being curable by contact therewith of from 5 % to 60 % based on the weight of said aqueous solution of a c 1 - 3 alkyl formate .