How sea salt is produced (comparison of sea salt, rock salt and refined salt)

What anyone would imagine sea salt to be:

artisanal salt production
sea water (a) which enters (b) into a pond (c) and evaporates there.... Thus it is only produced by very small artisans in very few places. How it is normally produced is explained below.


What gives salt its salty taste is sodium chloride. There are several types of salt but they are all very similar because the law requires that all salt for human consumption has at least 97% sodium chloride (whether refined or marine or rock). Sodium chloride is only 78% of everything contained in sea water, of everything that remains if we let sea water evaporate in a container. We also need the rest of the components (e.g. magnesium), and if it is lacking, it causes us discomfort (e.g. cramps).

alchemical symbol of salt
(alchemical symbol of salt)

In other words, the name of the salt, whether it is called sea salt (produced by the sea), or rock salt (from a mine), or refined salt, says nothing about its composition. Sea salt is sold with more than 99% sodium chloride.

Of the products I have researched, there is a "flower of salt" (not all), which contains only 91% sodium chloride.

Origin of salt

Salt comes from:

- From the salt mountains (rock salt).

- From the sea (sea salt, from coastal salt works)

- From saltwater springs (inland salt pans)

Types of salt

In order for salt to comply with the legislation (more than 97% sodium chloride), two methods are used:

  1. Refining (boiling) salt water (coming from a mountain), thus obtaining a purity greater than 99%(refined salt).

  2. Collecting only the sodium chloride from salt pans and not the other minerals, as explained below(sea salt).

(Rock salt is extracted from strata that are mainly sodium chloride or must be refined).

Refined salt

The largest consumer of salt is industry. Salt is used to make chlorine (by extracting the chlorine from the sodium chloride it contains) or hydrochloric acid or bleach. Chlorine is used to make PVC plastics. The industry is interested in a salt with the highest content of sodium chloride, and with the lowest content of other things that, besides not being of interest, are a nuisance to it. That is why the salt is refined, purified, to remove everything that is not sodium chloride, and is left with a content of more than 99% sodium chloride and less than 1% of other minerals.

This refined salt is the one most commonly used in the food industry (to manufacture everything from bread to any packaged product). And it is sold in stores, both in food stores, hardware stores (for swimming pools and water softeners) and cleaning stores (for dishwashers).

The pharmaceutical industry uses salt produced by an electrolytic process to achieve 100% purity.

Sea salt

It contains some more minerals than refined salt, as a result of the way it is obtained, but very little (less than 2%). It is used for the elaboration of salted fish (cod, sardines), baking and curing of hams (it is also sold in food stores).

Example of sea salt (99% sodium chloride). Click on "Technical data sheet" to see it.

How sea salt is obtained

We were taught as children that salt is obtained from salt pans by filling tanks with sea water and letting it evaporate. This seems to be the procedure used by some salt works, but the vast majority use the following procedure:

Salinas as they really work

The water is taken from the sea (1), enters the saline (2) and goes through different ponds (3),(4),(5),(6),(7), until it is returned to the sea(8).

Sea water contains several types of minerals, several types of salts. The most abundant is sodium chloride, but there are others, such as magnesium chloride, magnesium sulfate, etc. As it travels through the ponds (3 to 7), carbonates are deposited in the first, then sulfates, then sodium chloride(6) and then others before being returned to the sea.

The sodium chloride deposited in pond (6) is the one that is collected and sold as "salt", the rest of the minerals deposited in the other ponds are sold to the chemical or construction industry. (This is explained, for example, in this company ).

Result: the salt collected from pond (6) is almost all sodium chloride (more than 97%). These are not all the salts contained in sea water. If we put sea water in a decanter or in a pond (as we were told when we were children) and let it evaporate, we will have all the salts contained in sea water. See below the section: "What does sea salt contain".

After collection from the pond (6) it is washed (there are brands that do not, such as Danival).

What sea salt contains

If we put 1 liter of sea water in a tray and let it evaporate we will obtain (source of the data: P. Universidad C. de Chile) :

In other words, of all that will settle, 78% will be sodium chloride, 11% magnesium chloride, 5% magnesium sulfate, etc.

In other words, of the salt that we collect in the tray, 78% will be sodium chloride and 22% will be other things.

Those other salts are the ones that are removed to obtain sea salt or refined salt, with 97 - 99% sodium chloride and 3 - 1% of other things.


The best

Cooking with sea water. Typical dishes have always been cooked with sea water: from "papas arrugás" in the Canary Islands, to "pulpo a feira" in Galicia, etc.

As a minimum

Use sea salt for cooking without additives or "enrichments" (and take magnesium tablets from time to time?).

And the salt sold for livestock?

Cattle are also given a salt with more than 97% sodium chloride, as can be seen here. That supplier has another product with "only" 92% sodium chloride. All products start from sea salt containing more than 97% sodium chloride. Some products have less percentage because more additives are added, not because the original salt is better.

What about the salt used for roads?

As we can see here, they use salt with more than 98% sodium chloride.

Himalayan salt?

99% sodium chloride, as can be seen in this supplier (click on Himalayan salt data sheet).

Flower of salt?

The above supplier sells a flower of salt (from the Delta) with 91% sodium chloride and an appreciable amount of magnesium: more similar to the salt content of sea water (note: other flower of salt from the same supplier have a higher percentage of sodium chloride).

Frequently asked questions

Why is refined salt commonly used in bakeries instead of sea salt?

Because it contains more sodium chloride and an anti-caking agent (E-536 potassium ferrocyanide) so that the machines do not clog (the salty taste is given by the sodium chloride, which is in higher proportion in refined salt).

Why do some doctors recommend salt-free diets ?

Without sodium, neither the kidneys nor the nerves can function, as all physiology books explain.

what is better, to use salt or sea water for cooking?

Clearly it is better to use sea water because with it we are eating something that has the same chemical composition as the liquids of our body, much more similar than just water with salt (although when heated it has lost other properties that are not its composition).

Why is it that some dishes are cooked with sea water (since time immemorial) and others are not?


Why do we use salt instead of sea water?

There are reasons of convenience:

There were other reasons for the proliferation of salt:

There is a lot of (intentional) lies and (unintentional) errors.

The data provided by companies about their products are more reliable than those of websites that are not responsible for what they say, and their data and articles are not elaborated by professionals.

For example, in this website, they say that "all (marine, gem, refined) contain 100% sodium chloride", which is obviously false.

In wikipedia they state "Sea salt: is salt extracted from "integral" sea water in salt pans by evaporation. Sea salt has 86% sodium chloride (NaCl) and traces of trace elements such as calcium, magnesium chloride, potassium, iodine and manganese.": a whole bunch of errors / lies.


Article with curious and illustrative things about salt, with Cadiz grace.

ako-kasei.co.jp explain how in Japan people started to have high blood pressure since 1971 when they eliminated by law the coastal salt pans (and started to use refined salt).


BOE (Spain), which in its article 13.1.3 says "The sodium chloride content must not be less than 97 percent of the dry matter". FAO, saying the same in article 3.1.

In Mexico, salt for human consumption must contain at least 98.6% sodium chloride, and for the food industry 97.5 (even worse than that required by FAO).


In this salt company they explain that they have some evaporation ponds before the "salting" ponds (crystallizers), from where the salt is collected.

In this other one they also explain that the salt is collected from the "vasche salanti".

In this other one they explain the same thing: "vasche salanti o "casedde". "Li il sale si cristallizza e si raccoglie".

In Spain there is a convent of nuns (Poor Clares) who have declared that there is no pope since Pius XII. As a result, their "bishop" has stolen their bank accounts and is trying to expel them from their monasteries. He says they had less than 6,000 euros. (Even more shameful act, for stealing good poor nuns of what little money they had. They are poor: they had to mortgage one of their monasteries). They ask for support (money, materials or diffusion of their situation). Their website is tehagoluz.com and their Instagram account.

As you can see, on 6/14/2024 I've added many articles.

In Spain you can buy sea water at cheap price at any diet store and some supermarkets. Examples: this diet store, this pharmacy (at higher price), this supermarket.

There is also an organic bakery making bread with sea water and sells it too.

There are 5 companies bottling and selling sea water because there is a lot of people drinking sea water on a daily basis.

If you at your country become a critical mass of people interested in sea water, companies offering it will arise.

So, it's in your hands, sharing this information meeting your friends, by phone or social networks, to make the conditions where these companies will appear and make sea water even more available to all the people.

Work in progress.

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