Technical Notes
The support is a twill-weave canvas with eighteen threads per centimeter vertically and nineteen threads per centimeter horizontally. The canvas appears to have been artist primed with a warm white ground. Cusping in the fabric weave runs along all the edges. The ground application is thin and does not hide the texture of the canvas.

An initial loosely painted sketch was followed by a thin application of semitransparent dark paint in areas of shadow. The portrait was further developed with mid-tones and highlights applied wet-on-dry. Slight impasto is found on the white highlights.

Stuart made major compositional changes after he painted much of the portrait (fig. 1). He initially posed the sitter with her arms crossed in front but later depicted her with her arms raised, as if adjusting her mantilla. Due to the thin paint application, the first pose is still visible. Changes to the costume are also evident.

	Figure 1. Infrared reflectogram showing Stuart's changes to Sarah Morton's portait.

The painting was most recently varnished in 1983, when a spray coating of Acryloid B-72 was applied.

Frame Notes
The frame consists of a gilded softwood molding of a three-piece construction and applied compo ornament. The bole is dark gray. The frame has a thin gilded liner, followed by a sight edge with foliate ornament. Next to the sight edge is a plain cove, followed by a large outer cove with shallow, alternating laurel wreaths and acanthus ornamentation. The top edge has a narrow flat. The back panel is gilded.