Fleur de sels are formed as a soft, translucent crust on the exposed surface of salty water when it evaporates quickly. Fleur de sels have been collected from waters all over Europe and beyond, because its salts have a marine origin, which makes it ideal for preservation. It’s been used for millennia as both a curing salve and a natural preservative.

The seawater fleur de sel is formed in is usually salty, with a little bit of calcium and magnesium dissolved in it. As it evaporates, these chemicals interact with each other and create sodium, which is part of the saltiest part of seawater (which is also the most abundant). It’s this salty intermixture that gives fleur de sel its crunchy texture. In addition to lathering up with fleur de sel, however, it is also great as an addition to a wide range of snacks and breads, as well as being excellent as an alternative to regular salt.

The crunch of fleur de sel is achieved partly by the nature of its physical makeup: as mentioned, fleur de sel is made primarily of magnesium and calcium carbonate, with nothing else added. This allows the substance to be less affected by the additional effects of heat, therefore allowing it to be kept at room temperature, even in very cold temperatures. Because regular salt tends to crystallize in high temperatures, using fleur de sel is especially beneficial for keeping foods fresh and easy to eat, which is particularly important in places where access to traditional salt is limited. It can even be used in place of regular table salt in the cooking process to preserve foods for up to a few months; fleur de sel will not change the basic taste of any dish.

Another benefit of fleur de sel comes from how it behaves once it has been placed in water. Unlike regular sea salt, fleur de sel responds rapidly to changes in its environment, releasing ions that immediately change the surface texture of the liquid. This makes it a great addition to hot tubs, which can get too warm during the winter. As the water evaporates, the surface tension between the sodium ions increases, forcing water to rise to the top. As it reaches the top, the pressure changes again, forcing the water to fall again, forming a fluffy, luscious layer on the bottom of the tub.

In addition to its ability to quickly react to changes in temperature and physical conditions, fleur de sel is also great for use in damp or wet areas that are prone to water evaporation. Since it contains an extremely high concentration of sodium, it retains much of the moisture in seawater, preventing the loss of moisture through evaporation. Even during periods of dry weather, fleur de sel will continue to absorb moisture, which keeps it at the right moisture balance in most settings. It can even be used in artificial seawalls, further improving its ability to resist damage from salty weather.

Unlike ordinary sea salt, fleur de sel contains magnesium and calcium. The magnesium content allows it to improve the electrical conductivity of the seawater, making it better for electrical appliances and plumbing fixtures. The calcium content also improves the hardness of the seawater, making it more suitable for tooling in concrete and other construction materials. This natural brine also helps remove excess sulfur from the water, further reducing pollution from the burning of fossil fuels. As you can see, fleur de sel can benefit anyone who would like to minimize environmental impact by choosing to include this alternative form of salt in their cooking and baking recipes.