In In each stage, one can see the 3/8" steel rib lath attached to a wooden frame;
          then the trullisatio or scratch coat of plaster; then the arriccio or brown coat
of plaster with the sinopia drawing.

The trullisatio coat is usually made up of 3 parts coarse sand to 1 part lime putty.  However, in this portable model the modern product "structolite" was used to keep the weight down.  This coat is 1/2" to 3/4" thick.  The arriccio coat has been applied over the dry trullisatio starting with a 1/16" skim coat then building to a thickness of about 1/2".  This coat is comprised of 2 parts medium sand to 1 part lime putty.  The arriccio is allowed to set up until firm before the all important sand finish is "floated" on the surface using a wooden shingle float.  After a few weeks drying and carbonization of the surface, the design is transferred from the cartoon.  The cartoon is a drawing on heavy paper and has been scaled up from smaller study drawings to the full size of the fresco.  On heavy tracing vellum the main lines of the cartoon are first traced, then punched with a needle.  The back side of the tracing must be carefully sanded to smooth down the puckered, jagged pin holes that would otherwise ruin the surface of the fresh intonaco. Calculate your loans - mortgage calculator online.

Photo #1:  The purpose of the sinopia is two-fold.  First it allows the artist to view the composition as it will appear on the wall.  Any adjustments must be made at this time.  Secondly, the sinopia acts as a guide for laying each day's plaster in areas designated by the artist according to the amount of work he judges can be done in a day.  Each of these areas is known as a giornata. Against the dry surface of the arriccio the tracing is placed, and fine powdered red earth pigment is dusted on using a small cloth bag of same that is gently tapped and rubbed against the paper in the areas of the punched holes-a process called pouncing. The tracing is removed and the image is revealed as a dotted line drawing.  With a watery mixture of red earth pigment, the lines are drawn in by connecting the dots.  A little shading is usually done for fun and to increase the sense of form through chiaroscuro. In Photo #1 the dotted lines are most apparent near the bottom of the arriccio, and were purposely left for demonstration.

Photo #2 was taken at the end of the first day's painting.  The intonaco, made up of 1 part fine sand to 1 part lime putty, has been troweled onto the dampened arriccio starting with a 1/16" thick watery skim coat.  As the skim coat begins to set, the final coat of the intonaco is troweled on and built up to a total of 1/8" to 3/16" thickness.  This layer extends about 6 inches beyond the intended painting area and is covered with several layers of thin warm-green pigment known as the compitura.  This compitura serves both as a conditioning layer and a middle tone for the effects of chiaroscuro.  The spreading of the intonaco completely obscures the sinopia, so the tracing must be again placed on the plaster, lined up with the visible portions of the sinopia and pounced with the pigment bag.  The dotted lines are then quickly connected to re-establish the drawing.  Painting can now begin using colors pre-mixed by the artist.  The wavy, white line seen in Photo #2 is a cut made with the point of the trowel.  All intonaco plaster below this line is quickly scraped away.  Although beginning to set, this plaster is still wet.  Next, the exact contour of the day-line is determined and carefully cut and scraped away using wood cutting chisels, both straight and curved edged.  Some make this cut perpendicular to the surface; some bevel the edge at 45 degrees away from the painting.  There are pros and cons to each method.

Photo #3 shows the intonaco laid carefully right up to and joining with the final day-line cut.
The intonaco has been pounced but the dots are still unconnected.

Photo #5 shows the finished demo leaving the unfinished layers still visible.  As all the intonaco is still wet, colors are darker than they will appear when the fresco is dry.  This lightening of colors and value is calculated into the pre-mixing of the colors using experience and test panels.  The colors change dramatically over the first 2 weeks of drying and then more subtly over the years as carbonization will continue to take place, increasing the depth of values and richness of color.

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