Another header for this thread could be "Using salt weathering in a high-humidity environment".
In short, there's a few more steps to do before you can proceed to weathering. Salt is hygroscopic, so if any is left on the piece, you'll find a fine mist of water developing on it in a high-humidity environment. Naturally this is bad, so it will have to go before you can start weathering, etc. After you remove the salt, and once everything is "thoroughly" dry, do a taste test....it's crazy, but tap your tounge to random places on the piece. If it's salty, there's still some to remove. I quick run through tapwater worked for me, using an old toothbrush to gently hit the creases. All the residue came off cleanly, it tastes like paint (ah, childhood memories), and the finish still looks great!