Abstract: A method of making a number of foundry cores serially in which a foundry aggregate mixed with a curable binder is introduced into a core box cavity to form each green core which is gassed by passing into it a predetermined dose of a saturated vapor under pressure of a normally liquid curing agent for the binder and an inert carrier gas and then a purging gas is passed through the core to drive out unreacted curing agent. A ready supply of a saturated vapor of the curing agent is provided in a generating vessel. Once a body of the active liquid substance and overlying atmosphere of vapor is established in the generating vessel, the vapor is dispensed intermittently to the core box cavity in a series of bursts, one for each core gassed. Simultaneously with the dispensing of each burst, carrier gas is bubbled under pressure into a bottom zone of the vessel in minute bubbles so as to provide saturated vapor, replacing that dispensed.