What is the purpose of underpainting in art?

Underpainting serves as an essential foundational process in art, primarily designed to create a base for later layers and to help establish color values. Typically executed in a monochromatic or limited color palette, underpainting allows artists to lay down the basic shapes, textures, and tonal values of their piece before adding more complex colors and details. This initial layer can significantly influence the overall composition, guiding the artist in their color decisions and ensuring a cohesive interaction among the layers that follow. The technique helps to map out the light and shadow of the painting which is crucial for achieving depth and dimensionality in the final artwork.

While adding texture, creating final layers, or adding depth without color might seem like components of a painting process, these functions do not encapsulate the true purpose of underpainting, which is specifically about setting up the groundwork for subsequent artistic development.