The cross-linking, or cure, of Scot Bader Polyester Resin Crystic 139 (L.V.) was investigated by examining the resin during cure by means of acetone Soxhlet extractions and Barcol hardness tests. The experiments were designed to test Funke’s hypothesis that in the cure of polyester resins the nature of the final network is predetermined by conditions before the gel Point, and that post-gel conditions affect the rate of cure but not the nature of the final network and the final degree of conversion. Funke’s work was based on analysis of the final products of hydrolytic degradation of polyesters, which is quite different from the methods used in this investigation. It was concluded that the evidence did not support Funke’s hypothesis and explanations are afforded for this and suggestions for future work are recorded.