TotalBoat Polyester Structural Marine Repair Putty is not an air-dry product and should be fully cured and sanded before TotalBoat TotalProtect Epoxy Barrier Coat Primer is applied. You can spray PVA (polyvinyl alcohol) over the structural repair putty to starve it of oxygen and allow it to fully cure. You can also overcoat it with TotalBoat Gelcoat with wax or TotalBoat Polyester Finishing Resin, or cover the structural repair putty with plastic sheeting to starve it of oxygen. Once the structural repair putty has cured, dewax the surface with acetone and sand with 80-grit sandpaper before applying TotalProtect.