Magnesium Sulphate Heptahydrate - Cosmetic / Technical grade

MAGNESIUM SULPHATE HEPTAHYDRATE

Premium Technical & Cosmetic Grade 

Magnesium sulphate heptahydrate is a soluble crystalline compound with many applications. It is a type of salt and mineral which is found in the geological environment. This can be obtained from the ore, epsomite, a white solid substance found on the surface of the earth also it is in oceans and springs. Magnesium sulphate is commonly called Epsom salt or “bitter salt”.

Properties of Magnesium Sulphate:

• Synonyms: Magnesium sulfate heptahydrate; Epsom salt or “bitter salt”
• Appearance: off-white crystals
• Mg SO₄.7H₂O: >99%
• Magnesium sulphate (MgSO4): 49.1%
• Water: 50.9%
• Sodium: 40 mg/kg
• Potassium: 230 mg/kg
• Calcium: 60 mg/kg
• Chloride: 80 mg/kg
• CAS No: 10034-99-8
• EINECS No: 231-298-2
• Mol weight: 246.48
• Melting point: 1124 C
• Bulk density: 850 g/dm³ approx
• Density: 2.7 g/cm3
• Solubility: soluble in water 246 g/l in water at 20C
• pH: 5.0 - 8.0 at 50 g/L

Uses for Magnesium sulphate 

Healthcare & wellness

• Bath soaks & flotation tanks: Popular for muscle-soak rituals; very high concentrations increase water density for sensory-deprivation “float” tanks. (see below for guide on how to use)

Cosmetics & personal care

• Bath salts / scrubs: Bulking mineral salt; dissolves cleanly.

• Hair texturizing sprays (“beach waves”): Low % solutions of MgSO₄ add grip/texture. (see below for guide on how to use)

• Formulation aid: Can tweak viscosity/feel in emulsions (electrolyte effect), and acts as a mineral source in some skin/hair products.

Industrial / household

• Gardening / agriculture: Magnesium fertiliser (supplies Mg²⁺ for chlorophyll) and sulphur; used to correct Mg deficiency in plants (e.g., tomatoes, peppers, roses). Known for accurate composition, this fertilizer increases the productivity of crop plants and does not affect the fertility of the soil. (see below for detailed applications)

• Chemistry lab: Anhydrous MgSO₄ is a classic drying agent (desiccant) for organic solvents.

• Marine aquariums: See below

• Textiles & tanning / paper: Process aid and weighting/finishing salt. fire-proofing fabrics; dyeing and printing calicos;

• Manufacture of matches 
• Increasing the bleaching action of chlorinated lime; 
• Manufacture of mother-of-pearl and frosted papers; 

Using Magnesium Sulphate in marine aquariums

In an aquarium with low magnesium levels, calcium and alkalinity concentrations are difficult to control because there is a lack of magnesium present to stabilise these ions in the saltwater and prevent their natural precipitation into calcium carbonate.

You should aim to maintain Magnesium levels at around 1300 to 1350ppm using a good quality reliable test kit. 50g (10 teaspoons) will raise Magnesium levels by approximately 50ppm in 100 litres of salt water.

Simply dissolve the required amount into a few litres of Reverse Osmosis Water, mix well and slowly add to your tank in an area of high flow, preferably over a period of an hour or so using a drip line or peristaltic pump. Alternatively add to your evaporation top up water and top up as normal.

It is not recommended to increase Magnesium levels by more than 60ppm per day.

Garden feed (foliar spray & soil drench)

A. Foliar spray (quick Mg boost; low scorch risk)

• Magnesium sulphate (heptahydrate) …… 1.0–2.0%

• Water (tepid, low hardness if possible) …… q.s. to 100%

Example: 1 Litre batch @ 1.5%:

• MgSO₄·7H₂O 15 g, Water 985 g

Use: Spray to just before runoff, early morning/evening. Repeat every 10–14 days during active growth. Good for tomatoes, peppers, roses, citrus.
Tip: Add a 0.1% non-ionic wetting agent (e.g., alcohol ethoxylate) for better leaf coverage.

B. Soil drench (for confirmed Mg deficiency)

• Magnesium sulphate (heptahydrate) …… 10 g/L
  Apply 1–2 L per m² around root zone, water in well. Repeat monthly if needed.

⚠️ Avoid overuse on soils already high in Mg; on alkaline soils consider a soil test. Do not mix in the same tank with high-phosphate concentrates.

Bath salts (simple, fast-dissolving)

Target: Free-flowing crystals that dissolve clear and smell great.

1 kg batch example:

• Epsom 700 g, Sea salt 250 g, Bicarb 30 g, Frag 8 g, Tocopherol 2 g, Color q.s.

Method:
Tumble salts → add pre-blended fragrance + tocopherol very slowly while mixing to avoid clumping → add color last → pack with desiccant.

Beach-wave salt spray (texture with reduced dryness)

Clear leave-on hair mist (pH 5.2–5.8).

1 L batch (quick weights): MgSO₄·7H₂O 25 g, NaCl 7.5 g, Aloe 50 g, Propanediol 30 g, Panthenol 5 g, PQ-10 2 g (as a 2% slurry in propanediol/water), Protein 3 g, Preservative 8 g, Fragrance 2 g, Water to 1000 g.

Method:

1. Heat water to ~40 °C. Dissolve MgSO₄ then NaCl. Add propanediol, aloe, panthenol.

2. Slurry PQ-10 in a little water/propanediol, add under good stir until clear. Add protein.

3. Cool <35 °C, add preservative + fragrance.

4. Adjust pH 5.2–5.8. De-air and fill into fine-mist sprayers.

Use: Mist onto damp hair, scrunch, air-dry or diffuse.
Why MgSO₄? Gives grip/texture with less dryness than NaCl alone; PQ-10 and panthenol offset crunch.

Health & Safety:

Not a hazardous substance or mixture according to Regulation (EC) No. 1272/2008. This substance is not classified as dangerous according to Directive 67/548/EEC.

PLEASE NOTE: This product is not for human or animal consumption.

Click here for MSDS

Click here for Technical sheet