This gown is made of a very thin silk or taffeta with very fine stripes of red, blue and white, which, seen from afar, give the impression of mauve. A white leaf pattern is woven into the fabric and as well as floral sprays in various colours.
In the 18th century this dress would have been called a sack or sacque. This term seems to have first been used in the 1750s and was applied to gowns with a loose back. The fabric was set in folds below the shoulders from which it fell to the ground where it ended in a short train. The sack developed from an earlier gown worn for informal occasions, called in France a 'robe volante' or 'flying dress', presumably because of the shape it would have been produced when its wearer was moving forward.
This dress has a matching skirt, or petticoat, to give it its 18th century name. The front of the petticoat, the only part that would have been visible, is decorated with multi-coloured ribbon and delicate lace. The gown would also have had a matching stomacher, the triangular piece that filled the gap above the petticoat. The present stomacher is a reproduction.
The shape of the gown indicates that it would have been worn with a hoop petticoat, an invisible underskirt supported with rings of whalebone or cane.