Marcella says: Never use industrial salt, it comes from a chemistry laboratory! Use a natural salt. For example, use sea salt from the salt pans in Trapani.
I just read this post: Kate McDonough, The City Cook, describes the wonderful experience she had when she attended a cooking lesson with Marcella Hazan: “We were making the roasted eggplant, a recipe that first blister roasts the eggplant on the flame of a gas burner, then draining its excess liquid, and adding salt only just before serving. Mrs. Hazan abruptly grabbed the familiar cylinder of table salt and told everyone to stop what they were doing. ‘Never use this,’ she instructed, waving it in the air. ‘Americans think this is salt but this is from some chemistry laboratory. It only adds sourness. It adds no flavor. You will ruin your food.’ She went on to explain what salt is, where it comes from (the sea, underground, or laboratories), and how, as cooks, we must understand salt if we are ever to get the best flavors and results from our precious ingredients.”