the circles were raised a great part of the ink stuck to the slab. The two inks were then very thoroughly manipulated with a heavy knife until they were perfectly united, and the mixture was then put into a can which was numbered, and the color registered in a sample book made for that purpose. The greatest precautions were taken to avoid mistakes, which, of course, would seriously mislead the reader.
In mixing two or more colors it is of the utmost importance that everything should be clean. The stone or whatever is used to mix the inks upon, should be covered with boiled linseed oil, and then thoroughly cleaned with manilla tissue paper. The brass circles and the ink knives should be cleaned in the same manner. Then, when it comes to the mixing, the operator should not stop after he has rubbed the inks together for only a few minutes, but should keep at it, working lively until the inks are thoroughly united. Then, if the mixed color does not work well and lay smooth on the paper, it will not be on account of neglecting one of the most important essentials necessary to obtain that result.
All of the colors represented on Plate 1 were made as full bodied as they could be, to work well and print smoothly on the plate paper used. All of the proportions given for producing different colors by mixture, are based upon the use of full bodied or medium thick inks, and not upon very thin inks.
The different plates in this work are numbered consecutively from 1 to 90. The different figures shown upon the plates are numbered consecutively from 1 to 403. Every mixed color used in this book was made by the writer from the twelve colors shown on Plate 1. Of course, the special colors on Plate 86, and the bronzes and gold ink, are not included.
Plate 16.—This plate shows eight colors produced by three-color mixtures from the colors on Plate 1. The object of this plate is to show some deep colors, which could not be obtained by two-color mixtures.
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