PlatSil Part H Hardener can be used to increase the Shore Hardness of any of the PlatSil Gels. It also increases working and demold time. For Gel 00, a mix of 1A:1B:1H gives a Shore A10 rubber. For Gel 10, a mix of 1A:1B:1H cures to a Shore A20 rubber. For Gel 25, a mix of 1A:1B:1H has a 7 minute working time and cures to a Shore A40 rubber in under 2 hours.