Rivera painted all twenty-seven panels in the court himself. While methodical and almost mechanical in his persistence, he tried to maintain spontaneity even though the fresco technique of painting on wet plaster required him to plan carefully. Before Rivera began to paint, the panels were covered with several layers of sand and lime plaster, following a 15th-century recipe for fresco. Each succeeding layer contained less sand so that the final coat would be as smooth as marble.

Small sketches of each panel were enlarged to final size and pinned in place to allow Rivera to envision the final work. These full-scale drawings were called cartoons. Traditionally, cartoons are perforated along the drawn lines so that a fine powder, called pounce, can be dusted over them, thus transferring the image to the wall. The thirteen cartoons in the museum's collection have no perforations, and this is an indication that Rivera regarded them as more than working drawings. These huge drawings, unique because of their size and excellent preservation, are works of art in their own right.

Rivera's drawings were then traced onto tissue paper which was next perforated and pinned to the walls so that the guidelines could be pounced onto the second-to-last coat of plaster. The final coat of plaster was applied in small sections following major compositional lines to hide seams, and the mineral pigments were applied while the plaster was still wet. As it dried, the pigments reacted with the calcium hydroxide of the plaster and hardened, resulting in a chemically inert and moisture-proof surface.

Depending upon the humidity and temperature in the museum, Rivera had between eight and sixteen hours in which to work before the plaster set. In order to make best use of natural light, he would begin painting the black outlines and the gray shading before dawn under incandescent light. By dawn the monochrome outline of a particular section would be complete, and the artist could work in color by the natural light of the day.

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