Abstract: The invention relates to a method for the production of core preforms for foundry in which a) a mixture of inorganic, refractory foundry sand and a water glass-based inorganic binder is produced, b) the mixture is poured into a heated core box c) the water contained in the mixture is withdrawn by a physical method and d) the core preform is taken out of the core box. The process is characterized by the fact that e) the heated core box is subjected to a depression during filling f) the temperature/dwell time is adjusted after the closing of the core box so that a dimensionally stable and good bearing shell is formed on the edge of the preform g) the preform is immediately removed after opening of the core box and, under the effect of microwaves, is subjected to a complete drying.

Abstract: An apparatus for removing gases from molten metal, especially from molten aluminum. A ceramic or similar melting receptacle or crucible is accommodated in a furnace. A partial pressure is produced between the removable cover of the furnace and the surface of the molten material. Between the upper rim surface of the crucible, which is made of ceramic material, and the cover, there is disposed an intermediate ring which supports this cover. A sealing ring is disposed between the intermediate ring and the rim surface of the receptacle. This sealing ring is made at least partially of fibrous material which can resist high temperatures. At a surface pressure of greater than 15 kp/cm.sup.2, the sealing ring has a compressibility of at least 10% of its cross-sectional area.