The present invention concerns the curing and hardening of liquids comprising unsaturated resins, a peroxide and a chelant capable of chelating at least one transition metal ion through three, four, or five nitrogen atoms, which chelants may each optionally be complexed with one or two transition metal ions, typically iron or manganese ions. The invention also provides methods and formulations for making associated compositions, compositions resultant from the curing of such liquids and associated kits comprising two or more compositions physically separated from one another, which may be used to provide curable liquids when mixed.