Salt Shaker Converter

Salt is the oldest preserved food on earth. Roman legions were partially paid in salt rations - the salarium argentum, the literal origin of the English word salary. Caravans from the Sahara hauled blocks of salt across the desert and traded them ounce-for-ounce with gold in the West African empires of Ghana and Mali. The Via Salaria, one of the oldest Roman roads, was built specifically to move salt inland from the Adriatic. Every ancient civilisation built its trade routes around the stuff.

The biggest single change in American salt happened in 1924, when Morton Salt Company began adding potassium iodide to its table salt at the urging of public-health officials worried about the goiter belt of the upper Midwest. The Morton Salt Girl with her umbrella and the slogan 'When it rains it pours' - which referred to anti-caking agents that kept iodized salt flowing in humid weather - became one of the most recognised brand mascots in America. Iodized salt cut goiter rates by 90% within a decade.

Diamond Crystal Kosher Salt was launched by the Diamond Crystal Salt Company of St Clair, Michigan, in the early 20th century using a proprietary 'Alberger' vacuum-pan evaporation process. The process produces hollow pyramid-shaped crystals - very different from Morton's flat dense flakes. The two kosher salts share a name but are physically and culinarily different products: a cup of Diamond Crystal weighs 142 g, a cup of Morton weighs 240 g. This is the single most common cooking mistake in American kitchens.

The name 'kosher salt' refers to the technique of koshering - drawing blood out of meat by drying it with coarse salt - rather than to any religious certification of the salt itself. The larger, drier flakes of Diamond Crystal pyramid salt and Morton flake salt are both effective for koshering because they pull moisture without sliding off the meat. Most American restaurants moved exclusively to Diamond Crystal in the 1990s because it dissolves quickly and lets cooks season by feel rather than by precise measurement.

Sea salt prices were once exclusively the realm of luxury hotels. Fleur de sel - the 'flower of salt' - is hand-harvested from the top film of seawater evaporation ponds along the Guérande coast of Brittany and sold for 100 times the price of table salt. Maldon Sea Salt from Essex, England, in its characteristic flaky pyramids, became a chef's darling in the 1990s. Modern home cooks now have access to half a dozen luxury finishing salts that would have been restaurant-only a generation ago.

Himalayan Pink Salt is the modern marketing miracle. Mined from the Khewra Salt Mine in Pakistan's Punjab region (not actually the Himalayas), it is 98% sodium chloride with trace iron oxide for the pink colour. Almost every health claim made about it - more minerals, lower sodium, better hydration - is false. It is chemically and nutritionally indistinguishable from a mid-grade sea salt at five times the price. But the colour is genuinely pretty and the marketing genuinely effective.

Kala namak is a different story. The Indian black salt is genuine volcanic mineral salt with a real sulfurous content from kiln-roasting the salt with charcoal, bark, and seeds in the traditional process. The aroma is distinctly eggy - it is the secret behind vegan tofu scrambles and chickpea omelettes - and the chemistry is not duplicable by adding sulphur to ordinary salt. Its sodium content is slightly lower than other salts because some of the mass is genuine non-NaCl minerals.