People who choose to buy their dress may opt for finer fabrics, such as poplin, grosgrain, percale, cotton, wool, cassimere, broadcloth, Russell cord, or corded/ribbed material. For silk, there are a range of types including artificial silk/rayon, Ottoman (i.e. ribbed or corded silk), taffeta, satin, alpaca, true silk, shot silk, or a mixture. Pure Ottoman silk is rarely used except for official gowns, as it is very expensive. Some gowns may be trimmed with gimp lace, cords, buttons, or other forms of decoration.