The half-tone process is used almost exclusively for reproducing photographs and wash drawings, though it will produce a facsimile of any kind of copy, such as impressions from type, old manuscripts, or typewriting, but a shade composed of minute black dots will appear over the entire print and there will be no absolutely whits areas unless they are produced by routing the plate or cutting out the high lights. (See p. 74.) The reproduction of an ordinary outdoor photograph requires very little handwork, except for re-etching, burnishing, and cutting the borders. In the reproduction of copy that is made up of separate parts, such as groups of photographs of specimens that are to appear on a white ground, the half-tone "tint"--or more properly shade--between and around the several figures must be removed and numbers must be added. This operation requires two negatives--one half tone and one line--and produces what is called a "combination" plate. Therefore the difference in the cost of making a half-tone cut from a single photograph of a landscape and from a cut made from "copy" of the same size consisting of a number of small photographs or drawings, to which numbers or letters are added, is considerable (about 50 per cent greater) and depends upon the amount of additional work involved. Routing, when needed, must be done with extreme care lest the edges of a figure be marred, and this work requires skill that can be gained only by experience. Copy for the half-tone process should be as nearly perfect as possible. Only the best photographs should be selected. Prints on semimat velox and glossy haloid papers are regarded as the best photographic copy for reproduction. Every part of the photograph or drawing should be absolutely clean. If any part that should be pure white becomes soiled or stained the defects will be reproduced. If a photograph needs retouching it should be retouched with great care and just sufficiently to correct defects and to bring out or strengthen the important details. In many photographs the skies may be "muddy" or uneven in tone, and this defect can be corrected by the use of an air brush, the only medium that will produce an almost even tone. As already stated, half-tone plates can be improved by re-etching and tooling, but tooling tends to destroy the effects of nature and produces an artificial appearance in the print. One who is preparing wash drawings for reproduction by the half-tone process should remember that brush marks and other inequalities of tone will be reproduced with as much fidelity as other details. Such drawings should therefore be made two or three times larger than the engraved cut in order to subdue all unnatural effects and to soften the general tones.