This impression only hints at the underlying structures of the visible objects. Painted in oils upon canvas in 1874, the predominant colour in this painting is grey, the fog of the title. The objects in the painting, the trees on either side, the stooped figure of the woman and the bank of flowers in the foreground, emerge like ghosts from the mist or fog. The artist has created distance by rendering the less dominant trees, fencing and growing frames in even paler greys, to give the viewer a sense that he is looking into a three-dimensional garden.
The majority of Impressionist paintings were rendered en plein air, that is, in the open air, spontaneously and without preparation. The oil medium is typical of Impressionist paintings, since this robust material became available in portable tubes in the 1800’s, enabling artists to work out of doors. Working rapidly, they used broad, flat daubs of pigment to build their images. In this respect, Sisley is unlikely to have followed this outdoor tradition, since the subject material of Fog, Voisins would have made this technique improbable. Instead, he certainly constructed the image from existing sketches of working peasants, plants and trees. Even so, this painting is unmistakably Impressionist, since this group of artists became expert at rendering light and shade through the use of colour.
The profusion of delicate, lemon-tinted flowers in the foreground provide the painting's hint of colour. In accordance with the hinted-at objects in the background, this colour gives the painting a sense of depth. Visual harmony is created by these shimmering, lemon flowers that dwindle to a faint avenue as they thread into the background. On the painting’s right, the figure of the woman echoes the droop of the tree behind her, mirroring vaguely the bowing trees on the left. The woman, in motion while she works, is so adeptly frozen in time that Sisley’s rendering of her is almost photographic. In this image, the bank of warm, lemon flowers is the focal point in the midst of the cold, grey shades, adding a lovely and poetic touch to the composition. Today, Fog, Voisins can be seen in the Musee D'Orsay in Paris.