Orozco worked in the old western mural tradition, called buon fresco or true fresco. This is a demanding and unforgiving technique in which pigments are mixed into water and applied to wet plaster. It requires the artist to work quickly and accurately, applying pigment before the plaster dries. Once the plaster and pigment have dried, adjustments cannot be made. Using this technique, Orozco completed a new section of the mural each day. Looking carefully at the mural, one can find the slight delineations that indicate each day鈥檚 work. The surface of the fresco is vulnerable and, once damaged, difficult to restore to its original appearance. Since its completion there have been several projects to clean and stabilize the painting. In 1982, conservators discovered that bricks lining the chimney behind the central figure had begun to crumble, endangering the entire wall. In a complex process, the wall was reinforced from behind, saving the mural. More recently, the painting has been thoroughly cleaned, small areas of paint loss replaced, and new lights installed.