24 - 48 hrs for useable but it takes up to 7 day for complete curing, but generaly after 48 hrs it is OK for use in saltwater. My self I fill with water after 48 hours and leave for 24hrs then drain and wipe all silicone surfaces you will more than likly have a film on it after this film is removed you can use. The film is from the curing process and if there is no film then cure is done to a depth that it is not leaching out to the surface. I do not atempt to use till it has been cured for atleast 48hrs, I have seen guys kill tanks by rushing things. Remeber the curing time also depends on how heavy it has been put on.

Bill