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How Does Intumescent Paint Work?

Updated: Oct 25, 2022

How Does Intumescent Paint Work?

Intumescent paint is a type of reactive paint that expands when exposed to heat, forming a char barrier that helps to insulate the underlying material and slow the spread of fire.

It is often used as a passive fire protection measure in commercial and industrial buildings, as it can provide an extra layer of protection against the spread of fire. Intumescent paint can effectively help protect your property from fire damage, and it is important to choose the right formulation for your needs.

What Is Intumescent Paint?

Intumescent paint works by undergoing a chemical reaction when heated to form an expanded, thermally insulating layer that can help protect against heat loss.

This expansion creates a thick, spongy layer that acts as insulation, protecting the underlying material from fire. This type of paint is most commonly used in architecture to create an attractive surface on exposed structural steel elements. Additionally, it is also widely used as a passive heat protection system in the steel fabrications, construction, marine, and aerospace industries.

Intumescent paint is typically available in two forms: spray-applied and brush-applied.

While both forms offer effective fire protection, spray-applied intumescent paint leaves a thicker layer that often needs to be polished to hide and protect the underlying steel element.

How Does it Works?

An intumescent paint works when it is subjected to heat.

At temperatures of around 200-250°C, a complex chemical reaction provides insulation from intense heat. An intumescent coating undergoes rapid sublimation and extends several times its initial thickness up to 100 times to create a stable, carbonaceous char.

When the paint is applied correctly, it can keep a building's steel structure from collapsing for up to 120 minutes, ensuring that the required fire rating levels (FRLs) are met. This amount of time also helps firefighters to bring the situation under control and for buildings to be evacuated.

Without encasing structural steel components in concrete, vermiculite, or fire-rated boards, intumescent coatings can achieve the required FRLs. This permits structural steel components to become an architectural feature of a building's design and potential cost savings.

It also protects the substrate from structural deterioration and collapse since steel deteriorates at temperatures above 300°C, resulting in structural collapse and jeopardizing firefighters' lives.

At temperatures around 200°C, intumescent paint reacts, protecting the substrate from severe heat.

Intumescent Paints for Passive Fire Protection in Structures

Intumescent paint is most commonly used in architecture to create an attractive surface on exposed structural steel elements.

The typical fireproofing spray provides a thick and spongy surface that requires a finished surround to conceal and protect the steel members. An intumescent coating provides the same level of protection in the form of a thin layer of paint.

Paint is applied to the steel in layers to achieve the thickness required to meet the building code's requirements for protection. A final coating of intumescent paint is applied to the steel. This paint is tinted with pigment to provide the desired colour.

The intumescent coating can also be applied to the wooden structural members. The protection of wood is more about preventing the spread of flames and smoke than it is about preventing the transmission of heat. A coating can be put to the wood member to offer a rating, but only if the painted appearance is acceptable.

How Long Does Intumescent Paint Last?

The performance of intumescent products can vary depending on the specific type of coating, with some providing 30 minutes, 60 minutes, 90 minutes, or even 120 minutes of protection.

These solutions are especially effective in situations or applications that require a high level of fire protection.

How Effective Is Intumescent Paint?

Most recently, Australian Fire Control’s work in Raine Square included spraying intumescent paint into a steel framing system to provide a level of protection and encasing the framing in aluminium to provide further protection from its surroundings.

The full documentation on this project is available on AFC’s 2022 Compatibility Statement, which can be accessed here.

Intumescent paint is an integral part of an effective passive fire protection system. When exposed to extreme temperatures, it rapidly expands to protect the surface that it's applied. This prevents, minimizes, or delays fire damage to building structures, ultimately providing time for occupants to evacuate safely.

Intumescent paint is specially formulated to delay the onset of fire and provide a barrier between the heat of the fire and the surface that which it's applied to. The paint works by charring when exposed to heat, creating an insulating layer that protects the surface from further damage.

In order to be effective, intumescent paint must be applied correctly and regularly maintained. When used correctly, it can provide an essential line of defence against fire damage.

Wrapping Up

In the event of a fire, it is essential that the structural frame of the building is adequately secured to prevent the materials from reaching their critical failure temperature, which could cause the structure to collapse.

Intumescent paint avoids this, and it's a great way to help protect your property from fire damage. It is an excellent option to consider if you are looking for an effective and affordable passive fire protection measure.

With the right preparation, intumescent paint can provide an extra layer of protection against the spread of fire. Make sure to choose the right formulation for your needs, and work with a trusted contractor to ensure that the paint is applied correctly.

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