What Is the Difference Between Rock Salt, Sea Salt, and Iodized Salt?

The first difference among the 3 salts is where they come from. Rock salt is mined from ancient underground sea beds, then crushed and sifted. Sea salt is made by evaporating seawater in ponds. Table salt is one of these two types that has been refined and finely ground; iodized salt is table salt with iodine added. Unrefined salts retain trace amounts of other minerals, which give them their pink or gray color. These minerals are present in such small amounts that they cannot be distinguished by taste in food; colored salts differ mostly in appearance.

The main difference shows up in volume. Fine table salt packs tightly into a spoon, while air remains between the crystals of coarse rock salt and flaky sea salt. For that reason, the same spoonful of flake salt may contain roughly half as much salt as fine salt by weight; coarse rock salt falls between the two. A recipe written for one type of salt may turn out under- or over-salted with another. Weigh the salt or use the type specified in the recipe. If you switch types, start with less salt and adjust to taste.

Crystal size also determines where a salt is useful. Fine salt dissolves quickly in mixtures and dough, so it is preferred for meatballs, bread, and cake, where salt needs to be evenly distributed. Coarse rock salt works just as well in soup, boiled dishes, and pasta water because the difference disappears once it dissolves in liquid. Flaky sea salt is valued for staying undissolved on the surface; sprinkle it over grilled meat, tomatoes, or dessert just before serving to leave small, crunchy points of salt in the mouth. Adding an expensive salt to a boiling pot turns it into ordinary salt.

Iodized salt behaves no differently from table salt in everyday cooking, and its taste cannot be distinguished. The difference appears in pickles and brines: iodine and anti-caking additives found in some brands can cloud the brine and darken the vegetables. For pickles, brined cheese, and olives, additive-free rock salt or salt sold for pickling is recommended. Unrefined rock salt can leave a fine sediment at the bottom when dissolved in water; let the brine settle and use the liquid from the top.

Keeping 3 types of salt at home is enough for most kitchens. Use fine table salt for dough, mixtures, and at the table. Set aside coarse rock salt for boiling water, soup, and pickling; it is inexpensive, and its coarseness does not matter once it dissolves in liquid. Keep flaky sea salt in a small jar for dishes that need a crunchy surface finish just before serving. Colored and expensive salts are optional; they look attractive on a plate but do not make cooked food taste different from ordinary salt. Whichever kind you use, measuring by weight in grams gives the same result.