  Before final finishing by hand a working proof should be printed from the plate by an expert plate printer, by which, what the plate needs can be determined before final proving. Have the plate proved on different papers, and with different colored inks, so as to judge the effect. Imperial Japan is the best paper, besides etching paper, India, thin Chinese and Japanese papers. The cost of proving per single proof is 25 cents for a 4 × 6 plate on Imp. Japan, about $2.00 per doz. same paper; etching paper, about $5.00 per 100—less for large quantities. A second-hand D press, suitable for printing large or small editions or for proving, can be bought in Boston or New York for from $75 to $100. For instructions in printing see Hamerton's "Etchers and Etching." Steel Facing.The life of a photogravure plate without steel facing does not last much beyond 75 impressions, so that if an edition is needed, send the plate to any good printer who will have it steel-faced for you; their charges are very moderate, about 50 cents for a 4 × 6 plate. The steel-facing is accomplished by first making the plate chemically clean, as before preparation for graining, only be very thorough in using an old tooth-brush to get out the dirt and in addition use chloroform before using potash. Then solder a copper wire on to the back. The negative wire is attached to the copper plate. To the positive pole of the quart Smee battery is fastened a bright steel plate same size of copper, in a gallon jar. The plates are hung from glass (Denison's.)
Filter, and let stand for 24 hours. Five (5) minutes will cover the plate with a thin film of steel. (Obernetter's.)"Place the copper plate in a porcelain tray on the bottom of which rests a brightly burnished copper wire, the negative pole. "The anode on the positive pole, a bright steel plate, is suspended over the copper plate, and kept in motion while the circuit is closed. A precipitate of steel, resembling silver in appearance, must instantly occur upon the copper plate, any air-bells to be removed. Five minutes is sufficient to deposit a perfect steel coating." Grease the plate after steel facing, to keep off the rust. Formula: (Obernetter's.)
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