Mme Pissarro Sweing near a Window, 1878 by Camille Pissarro

In October 1878, Pissarro took a studio in the rue des Trois-Freres, Montmartre, where this portrait may have been painted. The couple's fourth son Ludovic-Rodolphe was born in Paris on 21 November, and it may be that Julie is heavily pregnant in this painting, which would explain the cursory execution of the lower area around the sewing. Pissarro explored this theme of a figure at the window many times, exploiting the contre-jour effect of the light and trying various ways of linking the figure in with the window frame. Here the bent head and torso are carefully placed in an enclosed space backed by the window and curtain. Pissarro has concentrated on surface pattern in this painting, preventing the eye from "looking out" through the window by blocking it with the decorative swirls of the wrought-iron balcony. Beyond this the scene is lightly painted, blurred and ambiguous. Consequently, attention is focused on the face through strong compositional lines such as the frame and cross bar of the window, cut by her head, the pattern of the wrought-iron, the line of her arm and the stripes of her dress. As in other compositions, Pissarro helps to unify the painting by repeating curves - in the ironwork, Julie's hand, her forehead and particularly her hair and the stray curls on the back of her head.

In the late 1870s Pissarro's paintings became more thickly worked, with areas of matted impasto. Here the figure is painted very densely, with the flesh tones constructed from superimposed strokes of strong colour - greens, blues and reds. This contrasts with the light treatment of the background and centre foreground, where an area of buff- primed canvas has been allowed to show through the sparse dry strokes of paint to represent the sewing fabric that Madame Pissarro is working on.