PROCESS FOR MANUFACTURING A VITREOUS MATERIAL, FOR USE, IN PARTICULAR, IN THE JEWELLERY TRADE

摘要

Manufacturing process for a lead silicate based material having a characteristic colouring ranging from orange-tinged yellow to blood red, characterized in that it comprises the following stages: a) preparing a bath or molten mass of lead silicate, produced by mixing lead oxide PbO and silica SiO2 in such proportions that the ratio between the two constituents is 65 % by weight of lead oxide and 35 % by weight of silica, whereby the temperature of fusion is chosen in the region of 1000 and 1300 DEG C; b) introducing into the fusion bath obtained during the foregoing stage, copper oxide and a reducing agent, whereby the quantity of this addition is such that the concentration by weight of the oxide in the final product is in the region of 6 to 8 %, the temperature of the fusion bath being maintained between 1000 and 1300 DEG C; c) maintaining the fusion bath at rest always at the same temperature approximately between 1000 and 1300 DEG C in order to eliminate bubbles; d) heat treatment of the material obtained in this way at a temperature between approximately 500 and 800 DEG C during a period of time sufficient to form and grow the cuprite microcrystals (Cu2O); e) slowly cooling the mass obtained to an ambient temperature in order to prevent residual stresses forming therein.