This invention relates to foundry binder systems, which cure in the presence of sulfur dioxide and an oxidizing agent, comprising (a) an epoxy resin; (b) an ester of a fatty acid; (c) an effective amount of a oxidizing agent, and (d) no ethylenically unsaturated monomer or polymer. The foundry binder systems are used for making foundry mixes. The foundry mixes are used to make foundry shapes (such as cores and molds) which are used to make metal castings, particularly ferrous castings.