A portrait in red chalk — sanguine — the only confirmed use of this medium in the portrait drawings, and one that immediately places the work in a distinguished tradition: sanguine was the medium of Leonardo's figure studies, of Watteau's portraits, of the great French academic drawing tradition. Whether Sidney chose it consciously within that tradition or simply had a red chalk in hand is unknown, but the result has a warmth and immediacy that black pencil cannot achieve.
The face is seen slightly downward-tilted, the eyes closed or cast down in the attitude of someone absorbed in inner experience. The expression has a quality of withdrawal that is both peaceful and slightly melancholy — this is someone who has turned inward. The long loose hair falls on both sides of the face, rendered in broad sanguine strokes that have warmth without harshness.
The red chalk allows for a range of tonal values that gives the face genuine three-dimensionality: the lightest marks at the highlights, the darkest at the shadow zones under the chin and at the eye sockets. The result is more sculptural than the pencil portraits, the face having actual volume.
The shoulders and arms below — bare — are described in the same warm tones, the contours following the figure's physical reality without elaborating it. The composition has the intimate, warm quality that sanguine uniquely creates — a sense of looking at something lit by firelight or candlelight.
This is the only confirmed red chalk work in the portrait section, and the only one that puts Sidney directly in dialogue with the Renaissance and Baroque figure drawing tradition.