The primary difference between the TotalBoat Clear High Performance Epoxy hardeners is the working and cure times. The maximum application thickness is also dependent on which hardener is used. For slow hardener, the maximum depth per layer is 1/4 inch. For medium hardener, the maximum is 1/8 inch per layer, and for fast hardener, the maximum is 1/16 inch. For more information, reference the charts below and the technical data sheet.