Is Zinc Flammable? does it melt or burn? (explained)

From metal alloys to medicine industries, Zinc is widely used in various household and industrial products. As Zinc readily reacts with a wide range of substances such as acids, alkalis, and non-metals, you might wonder whether it reacts with oxygen or resists fire like other metals.

So, is Zinc flammable?

No, Zinc in its metal form is not flammable. It has a high melting point of 419.5°C (787.1°F) and a boiling point of 907°C (1665°F). Therefore, it doesn’t easily ignite or burn at normal temperatures. 

However, finely divided Zinc dust is highly flammable. In fact, Zinc powder can be explosive under certain conditions.

Let’s get into the details and explore the flammability of Zinc in its different forms.

Is Zinc Flammable

Does Zinc Burn Under a Flame?

Zinc metal can burn under certain conditions but typically doesn’t burn when exposed to a flame. In its metal form, Zinc has a relatively high melting point (419.5°C or 787.1°F), so it won’t vaporize easily.

So, what about its alloy Zinc and Zinc sheets? Below is the flammability of Zinc and its different forms-

Metal Zinc

When exposed to a flame, metal Zinc will initially melt and form a thin oxide layer on its surface. This layer of Zinc oxide acts as a barrier preventing further oxidation and combustion of the Zinc metal. Therefore, the metal Zinc is considered non-flammable.

However, if the conditions are right, Zinc can burn. For example, when Zinc comes in contact with a more reactive metal like magnesium or aluminum, it may react more violently with a flame and ignite. 

Besides, if the Zinc is heated to a high enough temperature in the presence of an oxidizing agent, it may undergo thermal decomposition and ignite.

Zinc Sheet 

As Zinc is a non-combustible metal, the Zinc sheet itself isn’t flammable. However, if an extremely thin Zinc sheet is exposed to high temperatures or an open flame, it may become hot enough to ignite nearby flammable materials.

Alloy Zinc 

Similar to pure Zinc, alloy Zinc is also not flammable as it’s typically made up of non-combustible metal. Zinc alloys are created by combining Zinc with other metals like aluminum, copper, or magnesium. In most cases, the alloy metals are non-flammable, just like Zinc.

While the addition of other metals can alter the characteristics of the Zinc alloy, it doesn’t change the non-flammable nature of the Zinc component itself.

Metallic Zinc Powder 

Powdered Zinc is highly flammable, and it’s a class 4.3 fire hazard. Metallic Zinc powder readily ignites and might cause an explosion if not handled with caution.

Can Zinc Be Explosive?

Yes, Zinc can be explosive when finely divided or in powder form. When high concentrations of Zinc powder are dispersed in the air and exposed to an open flame or high heat, it can explode violently.

Besides, if Zinc powder reacts with certain acids and alkali hydroxides, it can create potentially explosive hydrogen gas. Below are the reasons why Zinc powder becomes explosive

Can Zinc Be Explosive
  • High surface area: Zinc powder has a high surface area-to-mass ratio. So, more and more airborne oxygen can simultaneously react with Zinc and cause an explosion when heated.
  • Formation of a flammable mixture: When dispersed in air, the fine Zinc powder can form a flammable mixture. This mixture can easily ignite and cause an explosion when exposed to a source of ignition.
  • Contact with incompatible materials: Zinc powder can react violently when it comes into contact with strong acids or oxidizing agents. During the reaction, these agents release flammable gases resulting in an explosion in the presence of an open flame.

Is Zinc Metal Fireproof?

Although Zinc metal isn’t completely fireproof, it does have a relatively high resistance to fire. When exposed to fire, metal Zinc forms a layer of Zinc oxide on its surface. It acts as a protective barrier against further oxidation and combustion.

Is Zinc Metal Fireproof

However, a few Zinc compounds are commonly used as flame retardants thanks to their ability to inhibit or slow down the combustion process. These compounds include- 

  • Zinc oxide (ZnO): This powdery substance has a high melting point of 1975°C. Due to its fire-resistant properties, Zinc oxide is used as a flame retardant in a wide range of commercial materials, including natural fibers, wood, and polyvinyl alcohol (PVA).
  • Zinc borate (ZnB4O7): Another widely used inorganic compound, Zinc borate, is used as a flame retardant in polymers. It’s commonly used in plastics and textiles. Zinc borates also function as smoke suppressants and afterglow suppressants.
  • Zinc stannate (Zn2SnO4): Thanks to its high thermal stability, this Zinc compound is used as a flame retardant in polyolefins and other polymer systems. 
  • Zinc phosphate (Zn3(PO4)2): This compound is used as a flame retardant in rubber, plastics, and other flammable materials.

Frequently Asked Questions

1. Is Zinc plating flammable?

No, Zinc plating is not flammable, thanks to the metal Zinc coating. However, the material being Zinc plated could potentially be flammable. For example, if the material being coated is a flammable plastic or a material that could react with the plating process, then it could pose a fire hazard.

2. What happens to Zinc in the fire?

Although Zinc is relatively difficult to burn, it’s not entirely fireproof. So, when heated at extremely high temperatures, Zinc burns with a light blue flame. A layer of powdery Zinc oxide is produced during the process, which can suppress further combustion.

3. How do you handle Zinc dust?

Zinc dust can be explosive if not handled properly. To prevent fire hazards, be sure to wear appropriate personal protective equipment (PPE), including gloves, goggles, and a respirator.

Store Zinc dust in a cool, dry place away from sources of heat or ignition. When working with Zinc dust, use a local exhaust ventilation system to remove dust from the air.

Wrapping Up!

So, there you have it all. In our write-up, we’ve addressed the commonly asked question, ‘Is Zinc flammable.’ As it takes a huge amount of heat to burn Zinc metal, it’s considered non-flammable. However, it’s important to note that different forms of Zinc have different flammability.

While Zinc powder is highly flammable and explosive, Zinc borates are used as fire retardants in the polymer industry. So, always check out the product labels containing Zinc and be sure to handle it carefully.

Don't Risk It! Discover how often your fire extinguisher should be checked to avoid catastrophe.