This silk gown worn à la Polonaise was probably dyed with weld, a vegetable dye cultivated actively in France but originally of eastern origin. It was introduced in Europe in the eighteenth century and was highly valued for dyeing silk. It was often used with other European-grown dyes such as saffron, cultivated in Hungary and Spain, and sumac, grown in Southern Europe, to create different shades of yellow. It's use extended into the twentieth century.