For procurement managers, chemical engineers, and logistics coordinators sourcing magnesium chloride, precision in written communication is non-negotiable. A single missing detail in how you write magnesium chloride — whether it’s the hydration state, CAS number, or purity base — can lead to receiving hexahydrate flakes when your process demands anhydrous powder, or industrial-grade material when food-grade is required. In this guide, we break down exactly how to correctly write magnesium chloride in purchase orders, safety data sheets, technical specifications, and regulatory filings, ensuring your sourcing is error-free and your operations run smoothly.
Magnesium chloride isn’t a single, monolithic chemical. It exists as anhydrous MgCl2 (a highly hygroscopic powder), as the hexahydrate MgCl2·6H2O (crystalline flakes), and as liquid brine solutions at various concentrations. Each form has distinct physical properties, handling requirements, and end-use suitability. When buyers simply write “magnesium chloride” on a purchase order, suppliers are left to guess. That guesswork can result in:
Precision in writing magnesium chloride specifications eliminates these risks. It aligns technical, commercial, and regulatory expectations, and it positions you as a meticulous, knowledgeable buyer in the eyes of reliable suppliers like Hailei Chemical’s magnesium chloride product line.
The backbone of any correct magnesium chloride notation is the chemical formula. For the anhydrous form, simply write MgCl2. This denotes one magnesium atom bonded to two chlorine atoms. When water molecules are incorporated into the crystal structure, the formula changes. The most common industrial form is hexahydrate, written as:
MgCl2·6H2O (note the interpunct ·, not a full stop or x).
Never write “MgCl2*6H2O” or “MgCl2.6H2O” in formal documentation — the interpunct is the IUPAC standard. If your system cannot insert the interpunct, the text alternative “magnesium chloride hexahydrate” is acceptable. For procurement clarity, always pair the formula with the full chemical name: magnesium chloride hexahydrate (MgCl2·6H2O).
To avoid ambiguity, always include the appropriate CAS registry number. This is critical because many intermediates in the magnesium chloride production chain have similar names. The key CAS numbers are:
For food-grade applications, also include the E number E511. On a purchase order, writing “Magnesium Chloride Hexahydrate (CAS 7791-18-6), E511 food grade” leaves zero room for misinterpretation. Similarly, in shipping documents, using the proper UN number (not required as magnesium chloride is not classified as hazardous for transport under UN Model Regulations) and the correct technical name aligns with international trade compliance.
This is where the phrase “how to write magnesium chloride” becomes most practical. A well-structured specification line item transforms a vague request into a tight commercial requirement. Below is a template adaptable for different procurement scenarios.
For hexahydrate flakes (de-icing, dust control, industrial uses):
Magnesium Chloride Hexahydrate Flakes, MgCl2·6H2O, CAS 7791-18-6. Purity: 46.0% MgCl2 minimum (as MgCl2 on dry basis). Insoluble matter: ≤0.1%. pH (5% solution): 7.0–9.0. Particle size: 90% passing 4.75 mm. Packaging: 1000 kg big bag with PE liner. Origin: China.
For anhydrous powder (metal production, chemical synthesis):
Magnesium Chloride Anhydrous Powder, MgCl2, CAS 7786-30-3. Purity: ≥98% MgCl2. Moisture: ≤0.5%. Iron (Fe): ≤20 ppm. Heavy metals (as Pb): ≤10 ppm. Particle size: -80 mesh. Packaging: 25 kg vacuum-sealed PE bags in steel drums.
For liquid brine (dust control, antifreeze):
Magnesium Chloride Brine, aqueous solution. Specific gravity at 20°C: 1.30–1.33 g/cm³, corresponding to approx. 29–32% MgCl2 by weight. pH (neat): 6.0–8.0. Clarity: clear to slightly hazy, free of suspended solids. Delivery: bulk tanker ISO container.
Notice how each line item defines the form, analytical benchmark, and packaging. This level of detail directly impacts price, logistics, and fitness-for-purpose. When you request a quote from Hailei Chemical’s magnesium chloride sales team, these written specs allow them to match the exact stock or production batch to your needs without back-and-forth clarification.
Regulatory writing demands absolute nomenclature discipline. The product identifier on the SDS (Safety Data Sheet) must match the label and shipping papers. For magnesium chloride hexahydrate, the SDS Section 1 should read: Product name: Magnesium Chloride Hexahydrate; Chemical formula: MgCl2·6H2O; CAS No: 7791-18-6; EC No: 232-094-6. If you are authoring internal SDS documents for your own branded formulations, copying these identifiers from your supplier’s technical data sheet ensures GHS compliance.
For GHS hazard classification, magnesium chloride hexahydrate is not classified as hazardous, but it’s still essential to write the full chemical name. Abbreviating to “MgCl solution” on a customs declaration can trigger hold-ups. On import documents, always include both the commercial name and the IUPAC designation. For shipments to the EU under REACH, the written substance name must correspond to the registered tonnage band and end-use descriptor you have communicated.
Even experienced buyers can slip into these costly ambiguities. Here are the most frequent pitfalls and their corrections:
How you write magnesium chloride also depends on the application your procurement team is serving. Aligning written specifications with end-use requirements ensures you get material that solves the operational problem, not just a generic chemical.
For winter road maintenance, the specification should reference the relevant national standards (e.g., ASTM D632 for liquid de-icers). Write: Magnesium chloride hexahydrate flakes, 46% MgCl2 min, suitable for production of 30% aqueous solution for de-icing, meeting PNS 97 Type I requirements. For dust control, the brine is often the final product applied directly. Specify specific gravity and total chlorides. Our hexahydrate flakes dissolve readily into consistent brine, an important quality parameter to include.
Manufacturers of magnesium oxide (MgO) boards need magnesium chloride as a binder. Here, the written requirement must go beyond basic purity and address elements that affect board strength and durability. Typically: Magnesium chloride hexahydrate flakes, MgCl2 min 46.0%, Sodium (Na) max 0.15%, Potassium (K) max 1.0%, CaCl2 max 0.8%, insoluble max 0.1%. The alkali ion content is critical because it influences the molar ratio of MgO to MgCl2 and the formation of the 5-phase crystal structure. A savvy buyer writes these trace element limits directly into the RFQ to ensure board quality.
When specifying magnesium chloride as a coagulant (nigari), the written description must include the food-grade certification. Write: Magnesium chloride hexahydrate, E511, food grade, FCC compliant, CAS 7791-18-6, heavy metals (as Pb) max 5 mg/kg, arsenic max 2 mg/kg, sulfate max 0.15%. The physical form is typically flakes or a concentrated liquid. Always reference the applicable food chemicals standard to demonstrate compliance awareness.
For electrolytic production of magnesium metal, anhydrous magnesium chloride is the feedstock. The written specification drives the highest purity demands: Magnesium chloride anhydrous, MgCl2 min 98%, MgO max 0.5%, moisture max 0.5%, Fe max 0.05%, no visible discoloration. The oxide level is tightly controlled because MgO doesn’t dissolve in the molten salt electrolyte and causes sludge. Knowing how to write magnesium chloride specs this precisely immediately signals to the supplier that you are a technical end-user, enabling better price and quality support from a producer like Hailei Chemical, an experienced exporter of high-grade magnesium chloride.
Beyond the purchase order, long-term supply agreements often include a quality annex. This is where the detailed written description becomes legally binding. The annex should include:
By writing magnesium chloride into the QA agreement with rigorous detail, you build a quality assurance firewall that protects your production line from lot-to-lot variability.
International shipping requires clear, standardised marks. For magnesium chloride hexahydrate flakes packed in 25 kg bags, the printed label should read:
MAGNESIUM CHLORIDE HEXAHYDRATE FLAKES
MgCl2·6H2O, CAS 7791-18-6
Net Weight: 1000 kg
Batch No: HC20240815
Country of Origin: China
Manufacturer: Weifang Hailei Fine Chemical Co., Ltd.
For liquid brine ISO tanks, the placard should state “Magnesium Chloride Solution, X%” with the appropriate % filling. Getting this right eliminates demurrage charges from misdeclared cargo.
Mastering how to write magnesium chloride is a small investment that pays large dividends: shorter sourcing cycles, reduced risk of reject material, and smoother cross-border transactions. Whether you are drafting an RFQ, a technical data sheet, or a regulatory filing, the principles are the same — include the full chemical name, correct formula notation (with hydration state), the relevant CAS number, and analytical boundaries that match your application. As a responsible supplier, Hailei Chemical encourages this level of precision because it enables us to deliver exactly the product you need, when you need it.
Ready to put your precise magnesium chloride specification into action? Contact our team today for a customized quote on magnesium chloride hexahydrate flakes, anhydrous powder, or brine solutions. Let us match your written requirements with a reliable, cost-effective supply from our ISO-certified production facilities.
For procurement managers and chemical engineers, a clear magnesium chloride hexahydrate specification is the first line of defense against costly supply chain errors. Whether you’re sourcing for de-icing, dust control, fireproofing boards, or magnesium metal production, the chemical’s purity, physical form, and trace impurities directly impact operational efficiency and end-product quality. This guide unpacks every critical parameter you need to evaluate—from molar mass and solubility to industry-specific grades and supplier reliability—so you can secure a consistent, high-performance magnesium chloride supply.
Magnesium chloride hexahydrate (MgCl₂·6H₂O) is the most common hydrated form of magnesium chloride. It appears as colorless, deliquescent flakes or granules with a bitter saline taste. The compound readily absorbs moisture from the air, which makes proper packaging and storage essential. In the industrial market, hexahydrate flakes dominate because they offer a practical balance between high magnesium chloride content and stable handling characteristics. Anhydrous magnesium chloride powder and liquid brine solutions are also available for specific processes like molten salt electrolysis or dedusting applications.
Understanding the magnesium chloride product range begins with recognizing that the hexahydrate form is not simply a “wet” version—it is a distinct crystalline solid with its own thermal behavior and application profile. When heated above 118°C, it gradually loses water of crystallization, eventually converting to anhydrous MgCl₂. This dehydration behavior is crucial in fireproofing board production, where controlled water release provides passive fire resistance.
A robust magnesium chloride hexahydrate specification sheet includes several fundamental physical constants. Familiarity with these values helps you cross-check supplier data and ensure the product meets process requirements.
These magnesium chloride physical properties are not mere academic data points. For a dust control contractor, the high solubility and hygroscopic nature mean the product can draw moisture from the air to keep road surfaces damp longer, reducing water truck frequency. For a fireproofing board manufacturer, the decomposition temperature window dictates the thermal resistance performance of the final board.
When reviewing a supplier’s certificate of analysis, look for these core parameters that define a commercial-grade magnesium chloride hexahydrate specification:
Beyond purity, the physical form matters. Flakes are preferred for de-icing because they dissolve more slowly than powder, providing longer-lasting traction and ice suppression. Powdered hexahydrate is used where rapid dissolution is needed, such as in brine preparation. Granular forms offer dust-free handling. When discussing your magnesium chloride hexahydrate specification with a supplier, always specify the desired particle size distribution to match your application equipment.
The same chemical serves vastly different industries, and each demands its own nuance in a magnesium chloride hexahydrate specification.
For road and airport de-icing, the primary metric is effective temperature range. Magnesium chloride brine works down to -33°C, outperforming sodium chloride (-9°C) and calcium chloride (-29°C). A de-icing contractor should look for a high MgCl₂ content (≥46%), low calcium to minimize scaling on equipment, and consistent flake size for calibrated spreaders. Often, this grade contains a slight excess of magnesium oxide to buffer pH and reduce corrosion, making it less aggressive to concrete and steel than other chloride salts.
Magnesium oxide boards (MgO boards) are manufactured by reacting magnesium chloride with magnesium oxide to form magnesium oxychloride cement. The magnesium chloride hexahydrate specification here demands extremely low iron (<0.005%) to prevent discoloration and staining. Sulfate must be minimal to avoid efflorescence on finished boards. The molar ratio of MgCl₂ to MgO is tightly controlled; any deviation from the expected purity shifts the reaction stoichiometry and compromises board strength and water resistance. A reliable supplier provides not just a COA but batch-to-batch consistency, which is non-negotiable for continuous board production lines.
In electrolytic magnesium smelting, anhydrous magnesium chloride or highly concentrated brine is fed into molten salt cells. The presence of water or sulfate generates impurities in the final magnesium metal and can cause dangerous cell reactions. Smelters often purchase hexahydrate flakes as the starting material, then dehydrate them under a hydrogen chloride atmosphere to produce anhydrous MgCl₂. Thus, their magnesium chloride hexahydrate specification prioritizes low sulfate, low boron, and low iron to preserve metal purity. Standard purity for this application is at least 99% MgCl₂·6H₂O.
As a coagulant for tofu (nigari) or in the production of some cheeses, magnesium chloride must meet food additive regulations such as FCC (Food Chemicals Codex) or JECFA. The specification includes strict limits on heavy metals (arsenic < 3 ppm, lead < 2 ppm, mercury < 1 ppm), sulfate, and insolubles. In this market, the term “bittern” is often used, and the product may be supplied as a purified brine or flake. Buyers should request a food-grade certificate and verify that the manufacturing process excludes industrial co-products.
Exploring the uses of magnesium chloride salt reveals why granular specification data is so crucial. Each use case stresses a different property.
In industrial procurement, questions about magnesium chloride vs magnesium sulfate often arise because both are soluble magnesium salts with overlapping application areas. However, their chemistry and performance diverge sharply.
| Parameter | Magnesium Chloride (MgCl₂) | Magnesium Sulfate (MgSO₄) |
|---|---|---|
| Common hydrate | Hexahydrate (flakes) | Heptahydrate (Epsom salt) |
| Molar mass (hydrate) | 203.30 g/mol | 246.47 g/mol |
| Magnesium content | ~12% Mg by weight (hexahydrate) | ~9.9% Mg by weight (heptahydrate) |
| De-icing lowest temperature | -33°C | Not commonly used (ineffective below -5°C) |
| Soil stabilization / dust control | Excellent; hygroscopic, forms a durable crust | Less effective; dries into a powdery surface, limited hygroscopicity |
| Fireproofing board use | Key component in MgO cement | Not used; sulfate interferes with oxychloride phase formation |
| Food coagulant | Preferred for tofu (nigari) | Sometimes used but imparts bitter flavor due to sulfate |
| Agricultural supplement | Both provide magnesium; chloride may harm chloride-sensitive crops | Preferred for foliar feeding and Epsom salt applications |
For de-icing contractors, magnesium chloride vs magnesium sulfate is a straightforward decision: magnesium chloride works at far lower temperatures and resists refreezing longer. For dust control, magnesium chloride’s superior moisture retention reduces reapplication frequency. In fireproofing, magnesium sulfate is simply incompatible. Only in certain agricultural or pharmaceutical contexts might magnesium sulfate take precedence. Therefore, when sourcing for bulk industrial applications covered in this guide, magnesium chloride hexahydrate is the product of choice, and selecting the right specification ensures you capture these performance advantages.
Your magnesium chloride hexahydrate specification is only as good as the supplier’s ability to deliver on it consistently. A one-time COA that meets specs means little if the next shipment shows a drop in purity or an unexpected increase in iron. Use this supplier evaluation framework to protect your operations:
When you have a clear magnesium chloride hexahydrate specification and a supplier that meets these evaluation criteria, you de-risk your supply chain and gain predictable process outcomes.
Even experienced buyers can overlook details that lead to performance gaps. Avoid these frequent mistakes:
At Weifang Hailei Fine Chemical Co., Ltd., we view a magnesium chloride hexahydrate specification not as a static document but as a dynamic quality promise. Our production lines yield hexahydrate flakes with a consistent 46% MgCl₂ content, precision-controlled impurity profiles, and a variety of packaging options tailored to your logistics needs. We serve industries from road maintenance in Scandinavia to fireproofing board plants in Southeast Asia, with full regulatory documentation and third-party testing available for every shipment.
Whether you need a bulk order of de-icing grade flakes or high-purity hexahydrate for sensitive food coagulant use, our team is ready to provide a detailed COA, samples for trial, and expert technical consultation. Visit our magnesium chloride product page for complete specifications, packaging details, and typical application data. When you’re ready to lock in competitive pricing and reliable delivery, request your customized quote and we’ll respond within one business day with a tailored solution that meets your exact specification requirements.