More recently , synthetic velvets have been developed , mostly polyester , nylon , viscose , acetate , and mixtures of different synthetics , or synthetics and natural fibers ( e.g. viscose and silk ) . More recently , synthetic velvets have been developed , mostly polyester , nylon , viscose , acetate , and mixtures of different synthetics , or synthetics and natural fibers ( e.g. , viscose and silk ) .