Sea salt has been used in bathing and skincare rituals for thousands of years. The Greek practice of thalassotherapy, using seawater therapeutically, is among the earliest documented uses. On Saaremaa, sea salt and Baltic sea mud have been part of local wellness traditions long enough to be recorded in historical health resort documentation. But beyond tradition, what does sea salt actually do for skin, and how should it be used?
What sea salt is and why it differs from table salt
Table salt is essentially pure sodium chloride (NaCl), refined to remove other minerals. Sea salt, particularly less refined varieties like Celtic grey salt, Himalayan pink salt, and Baltic sea salt, retains a wider mineral profile alongside sodium chloride. This typically includes magnesium, calcium, potassium, iron, zinc, and trace amounts of iodine and other minerals, depending on the source water.
The mineral content of sea salt varies significantly by origin. Baltic Sea water has a lower salinity than the open ocean (roughly 0.5% vs 3.5%) due to high freshwater input from rivers, but it contains notable magnesium and potassium concentrations relative to its sodium content. Dead Sea salt has an entirely different profile, extremely high in magnesium chloride and potassium chloride with much less sodium than other sea salts, which contributes to its distinctive skin effects.
Exfoliation: the primary mechanical function
Sea salt is an effective physical exfoliant. The irregular crystalline structure of sea salt physically dislodges dead skin cells from the surface when rubbed against skin. Salt crystals dissolve as they contact moisture and friction heat, which means the exfoliation action starts firm and becomes progressively gentler as the crystals dissolve, unlike pumice or synthetic scrub beads which maintain a constant abrasive quality throughout use.
Salt scrubs work well for body skin on areas with thicker skin: legs, arms, shoulders, and the torso. They are generally too coarse for facial skin, where finer-particle exfoliants or chemical exfoliation is more appropriate. Salt should not be used on broken, sunburned, freshly shaved, or otherwise compromised skin, as the sodium chloride causes stinging and can impede healing on open skin.
In scrub formulations, the grain size matters. Fine sea salt provides gentler, more even exfoliation. Coarse sea salt is more vigorous and better suited to rough areas like feet and elbows. Many body scrubs combine sea salt with plant oils to provide lubrication during application, which reduces the friction intensity and leaves skin moisturised after the exfoliation.
Mineral absorption through the skin
The concept that soaking in mineral-rich water allows transdermal mineral absorption is widely promoted but scientifically contested. The skin barrier is specifically designed to prevent most things, including minerals, from penetrating. Intact skin is a highly effective barrier against ionic compounds like mineral salts.
Some research suggests that magnesium from magnesium-rich baths or Dead Sea salt baths can be absorbed through compromised skin (eczema, open pores during heating). A 2017 study in Nutrients showed increased magnesium levels in subjects who bathed in magnesium sulfate solution, suggesting some absorption does occur, though the amount and clinical significance is debated. For intact, healthy skin, transdermal mineral absorption from a sea salt bath is likely minimal.
What is more clearly supported is the anti-inflammatory and emollient effect of Dead Sea salt bathing specifically for psoriasis and atopic dermatitis. Multiple studies show reduced itching, scaling, and inflammation after Dead Sea salt baths. The mechanism is thought to involve osmotic effects on the skin, the anti-inflammatory magnesium content, and improved skin barrier function, rather than systemic mineral replenishment.
Scalp uses of sea salt
Sea salt scalp treatments have a dedicated following among people dealing with excess sebum and scalp congestion. The logic is that salt’s osmotic action can help regulate scalp sebum production and the mineral content may support the scalp’s microbial balance. Salt is also mildly antifungal, which relates to its historical use in food preservation, and this property may help with dandruff associated with Malassezia overgrowth.
Practically, a sea salt scalp scrub (fine salt dissolved in a small amount of oil or applied to a wet scalp before shampooing) can remove product build-up and dead skin from the scalp effectively. It is a simple, low-cost alternative to dedicated scalp exfoliation products. Use once every one to two weeks rather than regularly to avoid over-stripping the scalp’s natural lipid balance.
Sea salt in formulations
In finished skincare products, sea salt appears primarily in scrubs, bath soaks, and occasionally in toners. In scrubs, it functions as the exfoliant. In bath products, it dissolves to create mineral-rich bathing water. In toners or facial sprays, it contributes minerals and the slight astringent effect of sodium chloride.
Salt sprays for hair are a separate category: the sodium chloride content creates a sea-textured wave by interacting with the keratin structure of the hair shaft, increasing friction between strands and enhancing natural wave patterns. The drying effect is intentional for this application but makes them unsuitable for already dry or damaged hair.
Estonia’s coastal tradition of using sea mud and Baltic sea water for skin has practical grounding in the mineral content of this specific body of water. Local sea salt in Estonian spa formulations carries the same regional relevance that terroir carries in wine, the origin shapes the mineral profile, and the history of use in that specific climate and culture adds context that mass-produced mineral products cannot replicate.