A guide to anhydrous zinc chloride, what it is, how it's used in metal finishing and beyond, and how it's supplied, from a US-based distributor.
Zinc chloride (ZnCl2, CAS 7646-85-7) is a white, deliquescent inorganic salt and one of the most water-soluble salts known. Its largest industrial uses are galvanizing and soldering flux, zinc electroplating, and activated carbon production. Stratus Chemical supplies anhydrous technical and industrial grade in moisture-tight packaging, with COA and SDS provided.
| Property | Value |
|---|---|
| Chemical name | Zinc chloride, anhydrous |
| CAS number | 7646-85-7 |
| Molecular formula | ZnCl2 |
| Molecular weight | 136.29 g/mol |
| EC / EINECS | 231-592-0 |
| Synonyms | Zinc dichloride, zinc(II) chloride, butter of zinc |
| Appearance | White to off-white granules or powder |
| Grades supplied | Technical / industrial, anhydrous |
| Packaging | Moisture-tight bags and drums |
Zinc chloride is a white, crystalline inorganic salt and one of the most water-soluble salts known. It is strongly deliquescent, not merely hygroscopic: exposed to humid air it absorbs enough moisture to dissolve into a liquid, which is why the anhydrous form is packaged to stay moisture-tight.
Chemically it behaves as a Lewis acid, accepting electron pairs from other molecules. That single property underpins most of its industrial roles. It is what lets zinc chloride strip metal oxides in a flux bath, catalyse condensation reactions in synthesis, and develop porosity in a carbon precursor.
Metal finishing is the largest use Stratus supports. Zinc chloride is valued both for cleaning and activating metal surfaces and for carrying zinc ions in plating chemistry.
In hot-dip galvanizing, zinc chloride is combined with ammonium chloride to form zinc ammonium chloride, the standard pre-flux. The flux removes residual oxide from pickled steel and leaves a film that lets molten zinc wet the surface cleanly. The ratio of zinc chloride to ammonium chloride, and the bath concentration, are set by the galvanizer's own process and the steel being coated.
Zinc chloride is the active component in classic acid or "tinner's" fluxes. It strips oxide from copper, brass, and steel at soldering temperature so the solder wets and bonds. It is often blended with ammonium chloride to broaden the working temperature range.
In acid chloride zinc baths, zinc chloride supplies zinc ions and raises bath conductivity, supporting bright, ductile deposits at high current efficiency.
Pickling and conditioning of steel and non-ferrous surfaces ahead of coating.
Zinc chloride is sold both as the anhydrous salt and as an aqueous solution. The trade-off is almost always freight and handling rather than chemistry.
| Factor | Anhydrous | Solution |
|---|---|---|
| Zinc chloride per pound freighted | Highest | You also pay freight on the water |
| Handling | Deliquescent; must stay sealed | Pumpable, no caking; corrosive liquid |
| Best for | Bath make-up where dry salts are already dosed; formulations that can't tolerate added water; long storage | Continuous dosing where tankage already exists |
| Cold-weather concern | None | Can freeze, depending on strength |
If you're shipping any distance and can keep product sealed and dry, anhydrous usually wins on delivered cost of zinc chloride. If you dose continuously and already have tanks, solution wins on labor. Stratus supplies anhydrous grade; if your process calls for solution, tell us the strength and volume and we can source to it.
Because zinc chloride is deliquescent, anhydrous product left in an opened bag will cake and then liquefy, and the assay drifts as water content rises. Keep containers sealed, decant only what you'll consume, and store in a dry area away from humidity swings.
Zinc chloride is corrosive and its solutions attack most metals, so use appropriate plastic or lined equipment. It is also hazardous to aquatic life. It is classified as corrosive for transport. Follow the SDS for hazard classification, PPE, spill control, and disposal. COA and SDS are provided with every shipment.
Zinc chloride is used in metal finishing as a galvanizing and soldering flux and in zinc electroplating, in activated carbon production as a chemical activating agent, in zinc-carbon dry cell batteries, in textile finishing, and as a Lewis-acid catalyst in chemical synthesis.
The CAS number for zinc chloride is 7646-85-7. Its molecular formula is ZnCl2 and its molecular weight is 136.29 g/mol. It is also known as zinc dichloride or butter of zinc. Stratus Chemical supplies anhydrous zinc chloride in technical and industrial grades.
Zinc chloride cleans and activates the metal surface and removes oxides, which helps molten zinc or solder wet and bond to the metal for a sound finish or joint. In hot-dip galvanizing it is combined with ammonium chloride to form the zinc ammonium chloride pre-flux.
No. Zinc ammonium chloride is a double salt formed from zinc chloride and ammonium chloride, and it is the pre-flux used in hot-dip galvanizing. Zinc chloride is one of the two starting materials. Galvanizers who blend their own flux buy zinc chloride and ammonium chloride separately.
Zinc chloride is a chemical activating agent. When a carbon precursor is impregnated with zinc chloride and carbonized, the salt develops porosity and produces high-surface-area carbon at lower activation temperatures than steam activation requires. It is one of the two main chemical activation routes, alongside phosphoric acid.
Yes, strongly so. Zinc chloride is deliquescent, meaning it absorbs enough moisture from the air to dissolve into a liquid. Anhydrous zinc chloride must be supplied and stored in moisture-tight packaging and resealed after opening.
Store it sealed in a dry area, and reseal opened containers immediately, because zinc chloride is deliquescent and will absorb atmospheric moisture. Stratus Chemical supplies anhydrous zinc chloride in moisture-tight bags and drums for this reason.
Yes. Zinc chloride is classified as corrosive and its solutions attack most metals. It is also hazardous to aquatic organisms. Handle it with appropriate PPE and containment per the safety data sheet, which Stratus Chemical provides with every shipment.
Stratus Chemical supplies anhydrous zinc chloride in technical and industrial grades, in moisture-tight bags and drums, with COA and SDS provided. Share your grade, volume, and delivery point and we will respond with pricing and availability within one business day.
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