Wilkerson Smith, Peter Nielsen, and Grayson Sayer. They rented a warehouse in the town of Tropico (now Glendale) near Eagle Rock. In Eagle Rock, a young artist named Conrad Buff heard of the project and applied for an assistant's position at $3.50 per day. Buff would stretch the canvases. Payne would then sketch out the painting. Buff would paint the sky and clouds, Payne and Smith would paint the foreground, Nielsen painted garlands and garlands of flowers, and Sayer and Payne would finish the foreground. By the end of the job, Buff was making $5.00 a day, eleven square yards of muslin were used, and ten thousand pounds of white lead paint.
Source: Libby Buff and George Stern, The Art and Life of Conrad Buff, 2000., Artists in California 1786 - 1940, Edan Milton Hughes, 3d ed.