Drawing Large

Whether chalk or paint, any large scale image begins with the drawing. And anyone who has studied drawing knows that the process of drawing involves as many lines or marks that you decide you don't want as those you do.

So where do those marks go? Mostly you don't see them on the finished piece, and in both chalk and fresco there isn't the time to make many marks that need corrected or erased altogether. Does that mean that artists doing these kind of projects don't make mistakes or corrections?

Of course not. We all make mistakes, even Michelangelo. But when working very large, or under a tight time restriction, or in front of as crowd, we make our mistakes (and corrections) ahead of time in creating templates for our work.

Michelangelo began each composition with small sketches, where he could find the shapes and forms he wanted to see in the finished work. When the sketches were perfected, they could be enlarged onto full size sheets of paper in outline form called cartoons, usually by assistants. Any errors in the enlargement process could then be corrected, or changes made to the composition, before a single stroke is applied to the actual fresco surface.

When the full scale cartoon was approved by Michelangelo, it was transferred to the fresco surface by a technique

called spolvero, (which) involved perforating the lines of the drawing on the cartoon with thousands of little holes through which a charcoal powder would be sprinkled, or "pounced", by striking the cartoon with the pounce bag and thereby leaving on the plaster an outline that was then reinforced in paint. (Ross King, The Pope's Ceiling)

In addition to the perfection of the drawing this technique offers a host of other benefits for its seemingly extra work. Remember, the wet plaster surface of fresco can only receive paint for so long before it cures, so the spolvero technique gets the artist a perfect drawing in the shortest amount of time, leaving the most time for painting. Also, if a section of plaster went wrong in the mix or cure and had to be removed and done over, the hard work of the drawing wouldn't be lost, because the perforated cartoon could be used over and over again.
For these same reasons, I use the spolvero technique in chalk painting as well as in many of my handpainted custom mural projects. Chalk painting happens over such a short time, I figure the audience doesn't want to see me puzzle over which lines to draw or see me make endless corrections to the outline, they want to see full color and dimension emerge from the pavement like magic. Similarly, I usually have some kind of paying audience when I do a custom mural in a private residence or public/commercial setting, and it builds confidence to see perfectly sized and corrected drawings appear onsite in minutes rather than hours.
In the same way that Michelangelo would want to keep drawing errors out of the fresh plaster surface because they are difficult to correct, a messy drawing in chalk or on a client's newly prepared mural wall makes the painting process more difficult because complete erasure in any of these mediums at large sizes is far harder than it looks and more time consuming than its worth, especially with someone watching you work.
And of course if a chalk painting gets wet or smeared, or if a mural wall is damaged or stained and need resurfaced, the spolvero drawing is ready to be used again anytime.
I have attached a series of pictures from my featured piece at Corso Degli Artisti to illustrate the use of spolvero. In the first picture, I am ready to put down the drawing of the central figure. You'll notice that she is already indicated in white primer contrasting with the grey background:

In fact, I already used this drawing to position her and lay down the white base before the panels were delivered to Little Italy. You can see the chalk smeared around the perimeter in this photo of the cartoon placed over the panels:

You can see the interior outlines from the perforations if you look closely. In the next picture, I've covered the drawing in black chalk and rubbed it through with a rag, making the image almost undecipherable:

After I lift the drawing, shake it out and fold it away, I'm left with a clean, accurate drawing in a matter of minutes while the audience watches:

One of the beauties of this technique is that the lines are so delicate they completely disappear into the developed chalk drawing:

I actually used this technique on each of the figures in this piece, as well as for the text that will finish it off. I also created spolvero cartoons for the small demo piece I did on TV (see earlier entries) and surrounding text. All of these drawings join my library of full size drawings from past projects, which can be reused in both other projects and in the teaching demonstrations I do at the San Diego Finishing School.