Abstract: When making a foundry mould or core from a fluid mixture comprising sand and a foamed aqueous phase comprising resin condensate, foaming agent and acid curing agent and that is a stable foam, improved results are obtained if the fluid mixture is obtained by forming a fluid mix of the sand, resin condensate and foaming agent and then mixing the acid curing agent into this.

Abstract: Particulate refractory material is formed into a mould or core and bonded with a binder including a polymeric carboxylic acid, a particulate inorganic material that will react with this to form a cement, water, and one or more of tartaric acid, phosphoric acid and fused particulate magnesia.

Abstract: Improved method for making foundry moulds and cores involves use of composition having foamed aqueous phase and comprising foundry sand, resin, curing agent for resin, silane, a low amount of water and a foaming agent such that the foam persists until the composition sets. Preferred features reside in having a total water content of from about 1% to about 2%, in using sodium lauryl ether sulphate as the foaming agent and in the order of mixing the ingredients.

Abstract: Particulate refractory material, e.g. foundry sand, is formed into cores, moulds and other shapes with the use of a binder comprising an ion-leachable inorganic particulate material and an organic polybasic acid or a precursor thereof which reacts with the ion-leachable inorganic particulate material in the present of water to form a binder which hardens the composition. Suitable binders are the polycarboxylate cements formed, for example, by reaction under aqueous conditions between zinc oxide or aluminosilicate glasses and polymeric acids such as acrylic acid polymers or copolymers.

Abstract: 1. A method of deceiving passive correlation measuring apparatus comprisingThe step of reradiating a plurality of substantial replicas of the target noise signature so separated as to provide a plurality of discrete correlatable signals for reception by said passive correlation measuring apparatus.

Abstract: Foundry moulds or cores are made by putting a mixture of foundry sand and acid-hardenable binder into a mould or core box, hardening the binder by passing an acidic gas through the mixture, removing the mould or core from the box and applying to its surface a material which will neutralise or adsorb acidic gases. The neutralising or adsorbent material permits avoidance of the health hazard of emission of acidic gas from the mould or core on storage or during use.