How to choose bath salts: a guide to the main types
Bath salts are mineral salts dissolved in warm bath water to change how the water feels and, if scented, how it smells. The five main types are Epsom salt, Dead Sea salt, sea salt, Himalayan pink salt and magnesium flakes, and each is a different mineral. Choosing between them comes down to texture, how the water feels, scent, and what is on the ingredient list.
Quick answer
- Bath salts are mineral salts dissolved in warm bath water to change how it feels and, if scented, how it smells.
- The main types are Epsom salt (magnesium sulfate), Dead Sea salt (a mix of mineral salts), sea salt and Himalayan pink salt (both mostly sodium chloride) and magnesium flakes (magnesium chloride).
- Choose by texture, how you want the water to feel and whether you want scent, and check the ingredient list for allergens.
- Follow the amount on the pack, run the bath warm, not hot, and soak for 15 to 20 minutes.
The main types at a glance
| Salt | What it is | Texture and dissolving | Typical use |
|---|---|---|---|
| Epsom salt | Magnesium sulfate, a single compound | Small, clear crystals; dissolves quickly | A plain mineral soak; the water feels soft and silky |
| Dead Sea salt | A mix of minerals, including magnesium, potassium, sodium and calcium chlorides | Coarse to fine, slightly damp crystals | A denser-feeling soak; the water feels smooth |
| Sea salt | Evaporated seawater, mostly sodium chloride | Fine to coarse grains or flakes; fine grains dissolve faster | A clean, lightly salty soak, much like the sea |
| Himalayan pink salt | Rock salt from Pakistan, mostly sodium chloride with trace minerals | Coarse pink grains; a little slower to dissolve | Much like sea salt; can tint the water faintly |
| Magnesium flakes | Magnesium chloride | Flat white flakes; dissolve very quickly | A magnesium bath without Epsom salt |
What are bath salts?
Bath salts are crystalline mineral salts made to dissolve in bath water. Some are a single mineral, such as Epsom salt. Others, such as Dead Sea salt, are a mix of several minerals. They are sold plain (unscented) or blended with fragrance, essential oils, botanicals or colourants. In cosmetic terms, bath salts work on the water and the surface of the skin only. For how they compare with bath bombs and other formats, see bath soak vs bath salts vs bath bomb.
What is Epsom salt?
Epsom salt is magnesium sulfate, a mineral compound named after the town of Epsom in Surrey, where it was first identified in spring water. It comes as small, clear crystals, usually in the form called magnesium sulfate heptahydrate (which simply means the crystals hold water within their structure). It dissolves quickly in warm water and leaves the bath feeling soft. See how to use Epsom salt in the bath for amounts and timing.
What is Dead Sea salt?
Dead Sea salt is salt collected from the Dead Sea, a salt lake between Jordan and Israel, and it is a mix of minerals rather than one. It contains magnesium, potassium, sodium and calcium chlorides, with much less sodium chloride than sea or table salt. The exact mix varies by source and batch. The crystals can feel slightly damp, because magnesium chloride draws moisture from the air. In the bath, the water feels dense and smooth.
What is sea salt for the bath?
Sea salt is salt made by evaporating seawater, and it is mostly sodium chloride, the same compound as table salt. It comes in grains or flakes of different sizes. A sea salt bath feels clean and lightly salty. Fine grains dissolve faster than coarse ones.
What is Himalayan bath salt?
Himalayan pink salt is rock salt mined in Pakistan, and it is mostly sodium chloride with small amounts of other minerals. Its pink colour is put down to traces of iron oxide. It is usually sold as coarse grains, which take a little longer to dissolve. In the water it feels much like sea salt.
What are magnesium flakes?
Magnesium flakes are magnesium chloride, dried into thin white flakes. They are a different compound from Epsom salt (magnesium sulfate), though both contain magnesium. The flakes dissolve very quickly. Our guide to the magnesium bath compares the two.
Epsom vs Dead Sea salt: what is the difference?
Epsom salt is a single compound, magnesium sulfate, while Dead Sea salt is a mix of several chlorides. Epsom crystals are dry and uniform; Dead Sea crystals vary in size and can feel damp. Neither is better. Choose by the texture and feel you prefer.
Scented or unscented bath salts?
Unscented bath salts contain only the salt, so they suit anyone who wants a plain soak or is sensitive to fragrance. Scented salts add fragrance or essential oils. Both can contain allergens, which by UK law must be named on the label above certain levels.
What to check on a bath salt label
The ingredient list, written in INCI (the International Nomenclature of Cosmetic Ingredients, the standard naming system for cosmetic ingredients), tells you what is actually in the jar. Look for:
- The salt itself. Magnesium Sulfate is Epsom salt; Maris Sal is sea salt; Sodium Chloride is salt in general; Magnesium Chloride is magnesium flakes. Dead Sea salt is often listed as Maris Sal or by its component salts.
- Fragrance allergens. Names such as Linalool, Limonene or Geraniol appear when present above the legal threshold.
- Colourants. These appear as CI numbers, for example CI 77491 (an iron oxide).
- Other ingredients. Oils, clays or dried flowers will be listed too.
How much bath salt should you use?
Follow the amount on the pack, as it varies by product. As a general guide, many plain bath salts suggest a handful to a cupful (roughly 100 to 250 g) in a full bath. Run the water warm, not hot, add the salt as it fills so it dissolves, and soak for 15 to 20 minutes.
Bath salts and sensitive skin
If your skin is sensitive, patch-test first: dissolve a little of the product in warm water, apply it to a small area of the inner arm and wait 48 hours. Unscented salts with a short ingredient list are the simplest place to start. If your skin reacts, stop using it. If you have a skin condition, check with your doctor first.
Where SLATE fits
Every SLATE block is a pressed bath block of about 22 g, and every block contains 10% Epsom salt. The SALT block is Epsom salt on its own. Other blocks build on that base with kaolin clay, colloidal oat or scent, so a Grid™ lets you choose how much salt, clay or fragrance goes into the water. The System explains how the blocks combine.
A Grid™ for a salt soak
12 SALT · Epsom salt
6 CLAY · Kaolin clay
3 OAT · Colloidal oat · Calm and soften
3 CALM · Lavender and chamomile · Quiet the noise
3 SOFT · Peach and magnolia · Be gentle
Build this Grid™ →
Common questions
What are bath salts made of?
Bath salts are mineral salts such as magnesium sulfate (Epsom salt), sodium chloride (sea or Himalayan salt) or magnesium chloride, sometimes with added fragrance or colourants.
Is Epsom salt the same as magnesium flakes?
No. Epsom salt is magnesium sulfate and magnesium flakes are magnesium chloride. Both contain magnesium but are different compounds.
Why is Himalayan salt pink?
Its pink colour is put down to small traces of iron oxide within the crystals.
Is Dead Sea salt the same as sea salt?
No. Sea salt is mostly sodium chloride, while Dead Sea salt is a mix of mineral salts, including magnesium and potassium chlorides, with much less sodium chloride.
Can I use table salt in the bath?
Table salt is sodium chloride, like sea salt, so it will dissolve in the water, but it may contain anti-caking agents or added iodine.
Do bath salts dissolve completely?
Most do in warm water. Coarse grains take longer, so add them while the bath is filling.
Sources
- Epsom Salts, University of Waterloo, Wat on Earth
- An Analysis of the Mineral Composition of Pink Salt Available in Australia, Fayet-Moore and others, Foods, 2020
- Bischofite, SaltWiki, HAWK University of Applied Sciences
- Regulation (EC) No 1223/2009 on cosmetic products, Annex III, legislation.gov.uk
SLATE products are cosmetics for external use only. If you have a skin condition, are pregnant, or have any concerns, check with your doctor before use. Patch-test any new product. Keep out of reach of children. Contains essential oils; see each block's ingredient list for allergens. Every block contains sweet almond oil (tree nut).
SLATE is a soak for the body and mind: small-batch bath blocks of cosmetic-grade ingredients, made in the UK. Build your Grid™
