INGOT IRON
Nearly chemically pure iron made by the basic open-hearth process and highly refined, remaining in the furnace 1 to 4 h longer than the ordinary time and maintained at a temperature of 2900 to 3100°F (1593 to 1704°C). In England, it is referred to as mild steel, but in the United States the line between iron and steel is placed arbitrarily at about 0.15% carbon content. Ingot iron has as low as 0.02% carbon. It is obtainable regularly in grades 99.8 to 99.9% pure iron. Ingot iron is cast into ingots and then rolled into plates or shapes and bars. It is used for construction work where a ductile, rust-resistant metal is required, especially for tanks, boilers, enameled ware, and galvanized culvert sheets. The tensile strength, hot-rolled, is 48,000 lb/in2 (331 MPa), elongation 30%, and Brinell hardness 82 to 100. Dead soft, the tensile strength is 38,500 lb/in2 (265 MPa), elongation 45%, and Brinell hardness 67. Armco ingot iron, of Armco Steel Corp., is 99.94% pure, with 0.013% carbon and 0.017 manganese. It is used as a rust-resistant construction material, for electromagnetic cores, and as a raw material in making special steels. The specific gravity is 7.858 and melting point 2768°F (1530°C). Enamelite is a sheet iron especially suited for vitreous enameling. Ingot iron may also be obtained in grades containing 0.25 to 0.30% copper, which increases the corrosion resistance. Iron of very low carbon content may also be used for molds and dies which are to be hobbed. The iron is quite plastic under the hob and is then hardened by carburizing. Plastiron is such an iron.
INK. Colored liquid or paste for writing, drawing, marking, and printing. Black writing inks usually contain gallotannate of iron which is obtained by adding an infusion of nutgalls to a solution of ferrous sulfate. Good writing ink is a clear, filterable solution, not a suspension. It must flow easily from the pen without clogging; give a smooth, varnishlike coating; and adhere to inner fibers of the paper without penetrating through the paper. It must have an intense color that does not bleach out. Ink is essentially a pigment in a liquefying and adhesive medium, but the iron-gallotannate writing inks develop their full color by chemical action and become insoluble in the outer fibers of the paper. For the proper development of the black color in gallotannate inks, a high percentage of iron is needed, and this requires a liberal use of acid, which will tend to injure the paper.Products, Inc., is a black ceramic ink that withstands temperatures to 2000°F (1093°C). These inks are ceramic solutions that must be heat-cured. Azo, triphenylmethane, vat, anthraquinone, and phthalocyanine dyes are common dye families used in ink manufacture. Flexographic ink and rotogravure ink may be made with cellulose-acetate-propionate ester resin which is soluble in alcohol and in other resins. When used with urea, it cross-links to form a permanent thermoset film.

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