§ 78 The Use of Cartoons in Mural and Panel Painting
When these cartoons are used for fresco or wall painting, every day at the junction with yesterday’s work a piece of the cartoon is cut off and traced on the wall, which must be plastered afresh and perfectly smoothed.192 This piece of cartoon is put on the spot where the figure is to be, and is marked; so that next day, when another piece comes to be added, its exact place may be recognized, and no error can arise. Afterwards, for transferring the outlines on to the said piece, the artist proceeds to impress them with an iron stylus upon the coat of plaster, which, being fresh, yields to the paper and thus remains marked. He then removes the cartoon and by means of those marks traced on the wall goes on to work with colours; this then is how work in fresco or on the wall is carried out. The same tracing is done on panels and on canvas, but in this case the cartoon is all in one piece, the only difference being that it is necessary to rub the back of the cartoon with charcoal or black powder, so that when marked afterwards with the instrument it may transmit the outlines and tracings to the canvas or panel. The cartoons are made in order to secure that the work shall be carried out exactly and in due proportion. There are many painters who for work in oil will omit all this; but for fresco work it must be done and cannot be avoided. Certainly the man who found out such an invention had a good notion, since in the cartoons one sees the effect of the work as a whole and these can be adjusted and altered until they are right, which cannot be done on the work itself.