Fresco - Sketches, Cartoons,
and Transfer Tracings

Before applying the intonaco, some artists trace or pounce the entire cartoon lightly on the sand-finish coat [the last coat before the intonaco]. Then with the design of the entire wall indicated on the sand-finish coat, it is easier for the artist, as the work proceeds on each section of intonaco, to keep the smaller areas related to the total pictoral plan. Excess charcoal should be dusted off the surface of the sand-finish coat before the intonaco is laid over it. By limiting the drawing to a light trace, the painter lessens the risk of interfering with the adhesion of the intonaco to the sand finish.

Until the middle of the fifteenth century, Italian fresco painters frequently painted the outlines of the main forms in their compositions on the sand finish before applying their intonaco sections. The pigment often employed for these compositional guides was a red earth color called sinopia. Some of these preliminary brush drawings on the sand finish have become visible when the intonaco over them flaked off as a result of faulty adhesion. Other sinopia drawings have been revealed as conservators have skillfully removed early frescoes from hazardous locations by peeling the paintings with their intonacos from their sand-finish surfaces.

Practice panels are very useful to help an artist to gain experience with the right methods for handling the mortar and with the behavior of the colors on the intonaco. Experienced painters sometimes make use of these panels to work out important detail sections of a large mural. Such a panel can be made by building a strong wooden frame out of 2" x 1 1/4" stock and nailing metal lath across the back of it. If the panel is large, it may be braced behind the lath with wooden cross pieces. It then should be plastered as described in the preceding sections, with the intonaco brought flush with the front edge of the wooden frame. Occasionally when it is not practical or convenient to paint the fresco in the room for which it is intended, similar panels are made and painted in the artist's studio and later installed in a wall.