Zinc borate is naturally occurring but can also be synthesized and used in a wide variety of industries. It’s an inorganic compound with a low toxicity used primarily as a flame retardant and smoke suppressing in plastic, fibres, paper rubbers, and textiles.

It’s also found in paints and fungicides and it looks like a white crystalline powder.

Zinc borate degrades endothermically, which means that it’s absorbing heat. As it’s absorbing the heat, it will start releasing its water of hydration at about 290° Celsius. This process helps reduce the intensity of the fire, which is why zinc borate is widely used in both based and halogen free systems. But, we will talk about these applications at length below.

Zinc Borate Applications

Because it has a low toxicity and it’s not considered hazardous, zinc borate has numerous applications in various industries.


Due to its flame retardant and smoke suppressing properties, zinc borate is widely used in paints and adhesives. When you combine it with zinc phosphate, for example, it acts as a corrosion inhibiting agent.

Polyamide Plastics

Polyamide plastics, such as nylons, have numerous applications in today’s industries. But, the toxic smoke and gas released from burning them as well as their heat prevents us from using them to their full potential. The good news is that flame retardant and smoke suppressant compounds can be used to control this.

To give you a more factual example, both phosphinate-based and halogen-free electrical insulator plastics use zinc borate as it acts as a promoting agent and suppresses the heat and afterglow.


In halogen containing systems, zinc acts as a char promoting agent. As the zinc borate releases its water of hydration, it creates a protective layer, thus minimizing the formation of toxic smoke. In this case, zinc borate works with antimony trioxide and alumina trihydrate, which also have flame retardant properties.

Zinc borate also has anti-drip properties and suppresses the afterglow.

In halogen free systems, zinc’s properties are enhanced when used with antimony trioxide and alumina trihydrate, magnesium hydroxide, red phosphorus, or ammonium. But, how does it work exactly?

As the plastic burns, a protective layer is formed, reducing the risks of toxic smoke and other potential issues.


Zinc borate is even used in agriculture both to protect the plant (as a fungicide) and to prolong its life (provides the necessary nutrition.)

Choosing the Right Distributor for Quality Raw Materials

When it comes to zinc borate, you can probably find lots of suppliers on the market, but few are as focused on quality as the Bisley company.

We offer a variety of zinc borates depending on your needs and the industry you’re in.

Get in touch with us online or call our team directly at +61 2 8905 4200.