ABSTRACTThe object of the investigation was to develop eutectic solvent for an enamel by the combination of several eutectics, then to add silica to increase the refractoriness of the enamel up to the limit of its capability to dissolve silica without endangering its bond to the metal body. This naturally involved a study of the entectic compositions of the RO–B2O3–SiO2systems. Since the Na2O–B2O3‐SiO2, K2O–B2O3–SiO2, and PbO–B2O3‐SiO2detormation eutectics are known a knowledge of the CaO‐B2O3‐SiO2system was necessary. A study of the high B2O3area of this system was made at approximately 4% intervals. A member high in CaO and SiO2, and which on repeated fusions showed practically 100% glass, was selected as a practical member to blend with the Na2O‐B2O3–SiO3and the PbO‐B2O3–SiO2eutedic to form a eutectic solvent for an enamel.Combinations of these eutectics and the CaO‐B2O3‐SiO2mixture were made and applied to cast iron by the dry process. Additions of SiO2were also made to these enamels up to 1.5 molecular equivalents. The physical properties of these enamels such as brilliancy, smoothness of surface, texture, bonding power, solubility in water, and resistance to a