A method of forming a working mold including: placing a substrate (610) on an electrode in a chamber, the substrate having at least a first structured surface (620) and the substrate including a thermoset polymeric material; introducing a release (630) layer forming gas into the chamber, wherein the release layer forming gas includes silicon containing gas and oxygen gas in an atomic ratio of not greater than about 200; providing power to the electrode to create a plasma of the release layer forming gas within the chamber; and depositing a release layer formed from the release layer forming gas on at least the first structured surface of the substrate to form a working mold.