Practical Lithography

tary D

ments-Preparation of Stones-Planing and Levelling-Grind

ly elementary in their character. It would be impossible, however, to regard them as non-essential, and a just a

veries which tended to materialise lithography as a graphic art, and may even be regarded as a f

ial results, yet without depreciating their merits, it will be but a fair recognition

es, and it undoubtedly reflects a vast amount of credit upon Senefelder that even at the outset he s

utely essential properties, and upon these is based almost every theory which has assisted in the development of this craft. These properties,

direction at least we must follow certain well-defined lines which may be re

al affinities is best calculated to impress upon the mi

es as an effect a design or impression which, to some extent, enters into the texture of the stone-the homogeneity of which checks any tendency to spread. T

achinery. The importance of each individual operation will be more readily appreciated when once its purpose is clearly understood. A litho-stone having a perfectly level surface is necessary in order to enable the printer to secure a firm and uniform pressure over the whole design when printing therefrom. A smooth, polished surface will

ay causes and effects. If, therefore, such a reference as the above to common details serves to convey some intelligent idea of their place and true value, then no apology whatever will be necessar

ntroduced to the trade. One of the more recent developments, a sto

imperceptibly lowered at each traverse of the machine, when they lightly cut away the surface of the stone until the old work is completely removed and a smooth level face is assured. The chief objection to this type of machine is that in course of time th

g.

principle, but one type differs from its contemporaries

ne makes no difference whatever, and the results are in the main uniform and satisfactory. The inconveniently sharp edges, such as are produced by the planing m

ing medium. To secure some degree of uniformity in the grain, and at the same time remove all the larger particles of grit, pass the sand first th

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iptical motion of one stone over the other with a s

considerable depth may appear on various parts of the stone's surface. These, in the subsequent polishing, may offer a strong temptation to the operator to work over one part of the stone more than

imilar character has considerably minimised the importance of the grained stone, inasmuch as it cannot now be regarded as an indispensable feature of lithography. It is, how

printing surface upon which the lithographic draughtsman can work with undoubted facility of exec

time coupled with intelligent application will be necessary to carry out this work successfully. Should the sand become too much worn before its renewal the grain will in proportion lose its "tooth" or sharpness. On the other hand lies the danger of producing a grain which is too harsh or pronounced. Therefore much depends upon the skill and judgment of the operator. A safe plan is to ascertain the progress at any time when a satisfactory result might be reasonably expected. The best way to accomplish this is by washing from the face of the stone any accumulation of sand, and drying it, so that a test can be made with the actual grade of crayon to be used in the subsequent drawing. A powerful current of clean, cold water affords the best means for removing every trace of sand from the f