Essentially a drying agent, this is designed to mix with the SF6500 primer base, SF6700 flex agent and the SF6820 reducer to use as the primer/filler coat in Superflite’s System VI. For complete and detailed instructions on the use of SF6600, consult the Superflite System VI manual. FAA-approved. Shelf life of 2 years unopened. Shelf life of 14 days opened. Mix ratio: 1 primer, 1 catalyst, 1/2 flex agent.