In the late 19th century, summer art colonies were becoming increasingly popular. Charles Hawthorne selected Provincetown as the site for his summer school, and he taught his students to do plein-air paintings—paintings out of doors. A model would sit on a stool on the beach, her face in shadow because of the broad-brimmed hat she wore to protect her skin from the sun.
Hawthorne was already experimenting with making his students paint with blunt-ended putty knives instead of brushes, and the model’s face in shadow created a featureless “mudhead” image that went well with that tool. He instructed students to only paint the broad patterns of light and shade, and not get caught up in the details. It taught them two fundamentals of modern painting: that the impact of a painting is in the broad shapes, not details; and that a sunlight effect is achieved through justaposition of these large color areas against each other.
“Make your canvas drip with sunlight,” Hawthorne told the students.