Use PlatSilPart H Hardener to increase the Shore hardness of any PlatSil Gel. It also increases working and demold time. For PlatSil Gel-OO, a mix of 1A:1B:1H gives a Shore A~10 rubber. For PlatSil Gel-10, a 1A:1B;1H mix cures to a Shore A~20 rubber. For PlatSil Gel-25, a mix of 1A:1B:1H has 7-minute working time and cures to a Shore A~40 rubber in under two hours.