The dots are of various sizes, ranging from a minute stipple to a solid black, and they present to the eye the same effect as the unbroken tones of a photograph. The negative when finished shows the drawing exactly like the original. The whites are opaque, the solid blacks are clear glass, the intermediate tones showing the same values in stipples of various sizes. The film of the negative is next removed from the glass, turned and placed on a heavier plate glass with a number of others and printed on a sheet of metal which has been coated with a sensitized solution.
This plate of heavy glass containing the several negatives is placed with the sensitized metal in a printing frame. The light passes through the clear part of the negative, the solid parts prevent the passage of light; thus we have the light acting chemically on the sensitized surface.
After the print is removed from the printing frame, it is developed, the parts acted on by the light adhering to the metal. The opaque parts, through which no light has penetrated, leave the solution soft on the surface of the metal. This is removed by placing in water and wiping gently with absorbent cotton. The print is then dried and heated over a stove which bakes the sensitized solution to the metal. It can readily be seen that this sheet of metal is now in such shape that the etching fluid will etch away the uncovered portions of the metal and allow the protected parts, which represent the color of the original, to remain in relief.
Line Engraving
This plate is etched—a flat proof, so called, is pulled on a hand press—and it is then taken up by the re-etcher. The re-etcher is the artist of the etching room. He takes the plate and by covering up certain parts and etching again gives additional play of color. Smaller developments of lights are worked out by careful manipulation of the etching fluid with small sable brushes. The differences in cost in the production of halftones is due largely to the length of time devoted to this work. The engraver or finisher then takes charge of it, preparing the engraving for the routing department, where the superfluous metal is removed. The plate is then returned to the engraving department, which completes the work, burnishing darks, engraving highlights, removing slight imperfections and otherwise perfecting the plate.
It is then proofed and blocked. Nine separate men handle each engraving in the halftone department.
The making of line engravings follows the same general course, with the exception that no halftone screen is needed, the copy to be reproduced being already made up of lines or dots or a combination of them. In the handling of line work, eight skilled men successively handle each plate.
Combination Engraving