| abstract |
A method for manufacturing pencil leads which comprises thoroughly mixing 100 parts by weight of graphite, 30 to 60 parts by weight of a water-soluble nigrosine, an emulsion containing 10 to 30 parts by weight of wax, and water together, extruding the resultant base mixture from a die into rods of a desired diameter, drying the rods to remove the water contained therein, and then baking the rods at elevated temperatures. The base mixture may contain 10 to 30 parts by weight of a water-soluble organic nonelectrolyte of high molecular weight such as cellulose ethers and/or not more than 10 parts by weight of carbon black in relation to 100 parts by weight of graphite so as to further improve the quality of the leads obtained. |