Intumescent Coating

Nullifire has pioneered the development and use of intumescent coatings for the fire protection of structural steel and timber for a generation. Nullifire systems are available for protection against both cellulosic and hydrocarbon fires, and also has a complete range of Water-based coatings providing 30, 60, 90 and 120 minutes fire protection.

Product Range
Nullifire’s range of intumescent coating products is divided into 3 specific areas.

What Are Intumescent Coatings?
Intumescent coatings provide an appearance similar to that of a paint finish, and remain stable at ambient temperatures.

However, in a fire situation the increase in temperature causes a chemical reaction, and the intumescent coating expands to many times its original thickness. This provides an insulating foam-like coating or ‘char’ which protects the substrate.

Protecting Steelwork
The intumescent coating is designed to insulate the steel, and prevent the temperature of the steel from rising above a certain point.

Protecting timber structures
Timber structures are more susceptible to the surface spread of flame and heat propagation. Intumescents are designed to reduce heat propagation, and reduce the spread of flame.

How Do Intumescents Work?
The expansion process is caused by the interaction of three precisely formulated components

1. Carbon Supplier: Polyols as starch, pentaerythritol
2. Acid Source: Ammonium polyphosphate
3. Expanding Agent: Melamine

Note: That the above components are bound in a solvent or waterborne polymeric binder. Other components are added to improve the paint properties and enable easy application, enhance build and achieve faster drying.

Typical Intumescent Process
As heat is applied the chemical reaction begins: -

1. The heat begins to soften the polymeric binder.
2. The heat also causes a release of an organic acid (from the Ammonia Polyphosphate)
3. Carbonisation of the polyols begins to take place.
4. Gas is then produced through the decomposition of the blowing agent (melamine), swelling the molten mixrure.
5. The final stage is solidification of the foamed char, through a cross-linking reaction, to maintain the insulation.

In an ideal situation the intumescent can expand some 100 times its original thickness. This requires the precise matching of various processes, which is achieved through careful selection of the formulation components.

See Intumescent in action

(note: opens in a pop-up window, you will need the Flash player to view it)

For further information please contact Nullifire Technical Services Department:

For guidance on which Intumescent Coating to use go to our Product Selector page.