[MWCC]

It will all depend on what type of media is used to blast the body. If the blaster uses soda or plastic media, you'll have a few days provided the humidity is very low. If they use anyting course like sand or aluminum oxide, you will need to prime it as soon as you get it home. Course media will open the pores of the metal and allow moisture to penetrate deep. It wont show right away, but when it does, it will come with a vengance. Most blasters will use course media in areas where there is visible rust or scaling. What I tell all of my customers is its better to be safe than sorry, etch or epoxy prime it as soon as you get it back from the blaster.