Abstract: Automatic molding apparatus to make flaskless molds from match plate patterns using sand and binder pre-mix and an activator or catalyst includes form boxes having open faces and double wall construction with a continuous chamber between the walls. The inner wall is vented to the chamber to provide a gas flow passage. The apparatus also includes manifolds which clamp over openings in the top and bottom walls for innoculation and pneumatic withdrawal of activating or catalytic-reacting gases such as hot air or carbon dioxide which are innoculated at an innoculation station into the mold box to decrease the hardening time of the sand. The open faces of the mold box are closed by hinge plates or cover plates each rotated by a rack and pinion. The plates are further secured during sand filling by spring-loaded arms bearing against tapered ribs on the hinge plates.