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The truth about sea / marine salt (and comparison between sea / marine salt, rock, refined / table salt)

We've always thought of marine salt extraction process as something like:

ideal salt evaporation pond as we all immagine
Sea water (a) enters through a channel (b) to a pond (c) where there evaporates. This salt doesn't exist in the market. Probably any company extracts salt in this way (maybe some artisans in very small ponds in the French coast). More explanation below.


In spite of its different names, all salts (we can find in the market) are very similar, because the law (at least in several countries), prohibits to sell salt with less than 97% of sodium chloride content. Salt obtained home-made by evaporation of sea water (as in the first diagram) would have only 78%, the rest would be other minerals we do not obtain when we buy salt in the store.

salt symbol
The composition of salts in the market has no relation with its name. There are sea / marine salts with more than 99% of sodium chloride.

From all the salts researched, only one brand of "fleur de sel" (not all brands), contains only 91% of sodium chloride.

Origins of salt

Salt comes:

- From mountains (rock salt)

- From sea (sea / marine salt)

- From inland salty lakes or sources.

Refined / table salt

Refined salt is obtained (regardless of its origin) mainly for the industry: to make chlorine (by extracting chlorine from the sodium chloride it contains). And chlorine is used to make PVC or other type of plastics. The industry is interested in a salt with the highest sodium chloride content, and with the lowest content of other minerals. That is why it is refined, purified, to remove everything that is not sodium chloride, and is left with a content of more than 99% of sodium chloride and less than 1% of the rest of minerals.

This refined salt is also the most widely used in the food industry (to make everything from bread to any packaged product). And it is sold in stores, both in food stores, in hardware stores (for swimming pools or softeners), and in cleaning supplies stores (for dishwashers). Really is a chemical product it shouldn't be sold for people or animals.

Sea / marine salt

It contains some more minerals than refined, but less than 2% of its weight. It's used in some food industries.

Example of marine salt (with a content of 99% of sodium chloride). Click on Ficha técnica” to see this data.

Sea salt extraction process (most companies use)

real salt evaporation pond

Water is taken from sea (1), through a channel (2) and it passes through several ponds (3),(4),(5),(6),(7), until finally is returned to the sea (8).

Sea water contains various types of minerals, various types of salts. The most abundant is sodium chloride, but it has others, such as magnesium chloride, magnesium sulfate, etc. By the effect of air and sun heat that evaporates water, different minerals are deposited in different ponds as the sea water passes through them (3 to 7). Firstly the carbonates, then the sulfates, then the sodium chloride (6) and then others.

Sodium chloride deposited in the pond (6) is collected and sold as “sea / marine salt”, the rest of minerals deposited in other ponds is sold to the chemical or construction industry. (This is explained, for example, in this company).

Result: the salt collected from the pond (6) is almost all sodium chloride (more than 97%). It doesn't contain all salts seawater contains. If we put sea water in a pond and let it evaporate, we get all salts sea water has. See below the section: “What does sea salt contain”.

After being collected from the pond (6), it is washed (although there are brands which don't do it, such as Danival).


The best

Cooking with sea water. Typical dishes have always made with sea water.

At least

Use sea salt without any additive (and maybe take magnesium from time to time).

And livestock salt?

No way. Normally cattle is feed also with refined salt.

And salt for routes in winter?

No way either.

Himalayan salt?

Look at its composition, but usually 99% of sodium chloride, as seen in this brand (click on "ficha técnica" of the Himalaya salt).


Why do bakers usually use refined salt ?

Because it gives more salty taste and machines work better with it.

Why do some doctors recommend low (no) salt diets?

All medical books explains kidney and nerves need sodium to work.


In Japan explain that, after being banned sea salt in 1971 (and used only refined salt), blood hypertension increases. Source:


BOE (Spain), in its article 13.1.3 sayEl contenido de cloruro sódico no debe ser inferior al 97 por 100 de la materia seca”. FAO, saying the same in its article 3.1.
In Mexico: salt for sale to the people must contain at least 98,6% of sodium chloride; and for the food industry 97,5. (Harmer even than the recommended by the FAO).

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