Abstract: In the course of this method, an amount of expansible mixture is poured into a mould, after which the mould is obturated by means of a plug. A vacuum is created in the chamber of the mould by way of the plug so as to cause the foaming of the mixture. The vacuum is maintained for a period after the foamable mixture has filled the whole of the volume of the mould. At the end of the polymerization of the foamable mixture, the vacuum may be re-applied in the mould, preferably for several cycles, so as to cause the cells of the foam obtained to burst.

Abstract: A mold-locking or catching device which comprises a support on one mold half or part, a bellows anchored to this support at one side of the bellows, a hook engageable with the rim of the other mold half or part and carried by the other side of the bellows and means for swinging the hook laterally into and out of engagement with the rim of the other mold half when the bellows is activated by fluid pressure or depressurized respectively.