Water and fresh blasted metal don't mix. You should just blow it off with air & a brush. I don't think there is a way to get rid of that rust haze now without reblasting. Even if you got a derusting chemical, when you rinse it off with water it will rust again, even if you quickly blow dry it.
Is that stuff "black beauty" , the slag material? I've never had that stick to a part before.