Why did Titian sometimes let the prepared canvas show through in his late paintings?

In his late paintings, Titian often allowed the prepared canvas to show through as part of a sophisticated technique that prioritized atmospheric effects and expressive freedom.12

Rather than applying paint in a uniform, opaque manner, Titian utilized a method where he tinted the white priming of the canvas with a brownish ground. He then applied oil pigments in varying thicknesses, using loose, free brushwork and sometimes even his fingers to manipulate the paint. By leaving parts of this tinted ground untouched or only thinly covered, he could effectively use the ground itself to provide halftones and suggest local or reflected color.21

This approach allowed him to create subtle transitions of light and shadow, or chiaroscuro, with great economy. The resulting works possess a fresh, spontaneous quality that conveys movement and emotional depth, prefiguring the dramatic style of later Baroque artists. Although these late paintings appear to have been executed quickly, they were the product of careful study and repeated reworking.21