What Is Zinc Chloride?

Zinc chloride (also called soldering flux) is a water-soluble chemical compound. Besides wood preservation, zinc chloride is used in various industrial applications, such as cement and paper-parchment production. It is an anhydrous salt, which can be prepared by reacting hydrogen chloride gas with hot zinc. In scientific laboratories, zinc chloride is a prominent catalyst and dehydrating agent.


Zinc chloride is a white crystalline granule. It usually has an acrid smell but is sometimes odorless. Zinc chloride is stable when stored and used under normal conditions, but when heated to decomposition, it can release toxic chlorine and zinc oxide fumes. Zinc chloride fumes when it establishes contact with cyanides, sulfides or potassium, which can cause fires or explosions. Its fumes are corrosive to metals.

Industrial Applications

Zinc chloride is used in dry cell batteries both as an electrolyte, moisture absorbent and corrosion inhibitor. It is used in fluxes for soldering, galvanizing and tinning. As an excellent emulsion breaker, zinc chloride is used to separate oil from water. It is also used as a packer fluid in oil and gas wells. Zinc chloride is put to use as an inhibitor in potable water treatment plants, cooling towers, and gas and oil wells.

Sources of Exposure

Exposure sources of zinc chloride in the workplace include working conditions including copper plating of iron, etching metals and soldering with fluxes having zinc chloride as well as galvanizing iron, arc welding of steel and iron pipes, vulcanizing and reclaiming methods in rubber manufacture and in the manufacture of smokescreen for military purposes. Proper ventilation and personal protective gear are necessary for ensuring the workers and other people in the area are not exposed to toxic fumes of zinc chloride.

Potential Health Hazards

Zinc chloride can destroy tissues of the upper respiratory tract and mucous membranes, in inhaled. If zinc chloride is ingested into the human system, symptoms such as burning sensation, cough, laryngitis, shortness of breath, wheezing, headache and vomiting will manifest. When zinc chloride fumes contact skin, it can lead to skin burn, ulceration and irritation. If the fumes contact eyes, it can lead to reddish eyes, blurred vision and pain. If zinc chloride solution is slashed accidentally on the eye, it can damage the eyes. If it comes repeatedly into contact with skin or inhaled, it can result in ulcerations of the skin and occupational asthma.


Zinc chloride can be stored in properly closed containers under cold to warm environment, in a temperature range of 2 to 40 degree Celcius. Damaged containers can be dangerous. Containers of zinc chloride can be dangerous even when empty because residues will remain as particles in the form of solids or dust.