Not All Salt Is the Same: Grain, Source, and Why It Matters.

The "salt is salt" crowd is not entirely wrong. Pure sodium chloride is pure sodium chloride — the chemical formula does not change based on where it came from or how it was processed. If you took perfectly refined NaCl from three different sources and dissolved equal amounts in identical water, you could not taste the difference, because there is no difference to taste.

But you are not eating dissolved crystals in water. You are cooking with them, finishing dishes with them, measuring them into recipes, and in the case of electrolyte blends, relying on them to deliver specific mineral profiles to your body. When you look at salt through those lenses — grain size, dissolution behavior, mineral content, sourcing purity — the differences become real and meaningful. Here is how to navigate them.

The Chemistry: What All Salt Shares

All culinary salt — regardless of type, origin, or marketing claim — is predominantly sodium chloride. The purity varies. Highly refined table salt is typically 97–99% NaCl, with the remainder consisting of anti-caking agents (most commonly sodium aluminosilicate or calcium silicate) and, in iodized versions, potassium iodide.

Less refined salts — including most sea salts, Himalayan pink salt, and artisan finishing salts — contain trace amounts of other minerals alongside the NaCl: magnesium, calcium, potassium, sulfate, and various metal ions depending on the geological or oceanic source. These trace minerals are real. Whether they are detectable by taste or nutritionally meaningful at typical culinary quantities is more nuanced.

Grain Size: The Variable That Changes Everything in the Kitchen

The most functionally important difference between salt types is not where they came from — it is grain size. Grain size determines dissolution rate, density per volume measure, and tactile impact when used as a finish.

Table salt is fine-ground, dense, and dissolves almost instantly. A teaspoon of table salt contains significantly more sodium than a teaspoon of kosher salt or coarse sea salt — this is why recipe conversions between salt types matter. Replacing a teaspoon of kosher salt with a teaspoon of table salt in a recipe will substantially oversalt the dish, because you are packing more sodium into the same volume.

Kosher salt has a coarser, flakier grain structure that results from a specific harvesting process. It dissolves more slowly than table salt and is significantly less dense by volume — a teaspoon of Diamond Crystal kosher salt (the less dense of the two major US brands) contains roughly half the sodium of a teaspoon of table salt. Professional kitchens favor kosher salt for its ease of handling (the large grains can be pinched and distributed precisely), its predictable behavior on meat surfaces, and because the absence of anti-caking agents avoids a bitter aftertaste that table salt can impart.

Flake salts (such as Maldon) are harvested using controlled evaporation processes that produce thin, pyramid-shaped crystals with a large surface area relative to their mass. They dissolve rapidly on contact with the tongue — before they reach the molars — delivering an immediate burst of salinity. This is why they are used as finishing salts: the sharp, instant impact is experienced as a more vivid salt sensation than the same sodium delivered in a dissolved, uniform form. Heat destroys this effect; flake salts are wasted in cooking applications.

Coarse and rock salts dissolve slowly and are best used in applications where extended contact time is available — brines, curing, and pasta water where a large volume of water will be heated for minutes.

Sea Salt: What the Ocean Actually Brings to the Table

Sea salt is produced by evaporating seawater — either through solar evaporation in salt pans or through mechanical processes — and harvesting the resulting crystals. The primary product is sodium chloride. The trace mineral content varies with the source ocean and the degree of processing, but is generally present at low enough concentrations that it does not meaningfully affect taste in most applications.

The less-discussed consideration with modern sea salt is contamination from the contemporary ocean environment. Research has established that microplastics are present in seawater at every depth and location that has been studied. A 2018 study published in Environmental Science & Technology found microplastics in the majority of commercially available sea salt brands tested across multiple countries, with concentrations varying by brand and processing method. A 2023 study by researchers at the State University of New York detected nanoplastics — particles smaller than one micrometer — in sea salt at higher concentrations than in rock salt or lake salt.

The long-term health significance of microplastic ingestion through food is still being researched and is not fully understood. For the general population, current dietary exposure to microplastics from salt is considered low relative to other dietary sources (seafood, drinking water, processed foods). For individuals managing conditions that involve heightened sensitivity to environmental contaminants, it is a reasonable variable to consider when selecting a primary salt source.

Ancient and Geological Salt: What Being Underground for Millions of Years Actually Means

Geological salts — including the Himalayan pink salt mined in the Khewra Salt Mine of Pakistan, and various ancient rock and mineral salts sourced from inland deposits — formed when ancient seas evaporated and were sealed under geological pressure over hundreds of millions of years. The salt deposits that exist today predate modern industrial pollution, synthetic chemicals, and the microplastic contamination that characterizes the contemporary ocean environment.

The mineral content of geological salts is determined by the composition of those ancient seas and the trace elements in the surrounding rock strata. Himalayan pink salt, for example, owes its characteristic color primarily to trace iron oxide content. Mineral analyses of various geological salts show the presence of over 60 trace minerals — present in concentrations that are real but typically too small (often parts per million) to be clinically significant as a dietary mineral source. The flavor contribution of these minerals is similarly subtle.

What geological salt does reliably deliver is a sourcing history that predates modern contamination. This is not a claim about superior nutrition — it is a claim about purity relative to a specific class of modern contaminants. For applications where ingredient transparency and supply chain integrity matter, the traceability of a geological salt deposit is a meaningful advantage over a sea salt whose ocean source may carry an unknown contamination profile.

It is also worth noting that geological salt harvested from North American deposits offers significantly shorter and more transparent supply chains than imported Himalayan varieties, with equivalent geological age and purity characteristics.

The Iodine Question

Iodized table salt was introduced in the 1920s as a public health intervention to address iodine deficiency, which causes thyroid disorders and was endemic in regions far from the ocean (including the American Midwest — historically called the "goiter belt"). The program was one of the most successful nutritional interventions in US history, effectively eliminating endemic iodine deficiency.

Modern diets in most developed countries provide iodine through multiple sources beyond table salt: dairy products, seafood, eggs, and many processed foods. The dietary iodine picture has become more complex as artisan and specialty salts (which are not typically iodized) have gained popularity and as table salt consumption from cooking has declined in households using kosher or sea salt. Individuals who avoid iodized salt entirely and do not consume significant amounts of dairy or seafood should confirm their iodine status with a healthcare provider.

What This Means for Your Salt Selection

Different salts belong in different roles:

• Cooking and seasoning through the process: Kosher salt or coarse sea salt or ancient rock salt — any consistent, anti-caking-agent-free option with a grain size you can control by feel. Consistency matters more than brand.
• Finishing: Flake salt. The physical structure is doing most of the work here. Apply immediately before serving.
• Baking: Fine grain salt for even distribution in doughs and batters. Be mindful of density differences when converting between salt types in recipes.
• Electrolyte applications: Source matters. Ancient geological salt eliminates the microplastic contamination variable and provides a traceable, stable mineral profile — which is why we use it.

Part 3 of this series closes with the question chefs spend their careers getting right: not just which salt, but when — and how the timing of salt application transforms results at every stage of cooking.