Salt and alcohol is the way to go. A friend of mine used the 420 cleaner, it seemed as though it was half salt and half alcohol with something to turn the liquid blue. They advise that you reuse the solution, so I decided to reuse an alcohol salt solution. Works like a charm. I use a large beverage pitcher to house the solution, and let my pieces sit in there as necessary. I then rinse them out in the sink, making sure to get all the salt residues out, then put them through the dishwasher to make sure its all gone and to free up any resin that may have become trapped in the piece.
Alternatively, I have found that if I am diligent about dishwashing my piece weekly, the solution is unnecessary. This also avoids the need to remove the salt film which seems to be impossible to remove in some irregularly shaped pieces.