New to working with intumescent paint coatings? Here are eight key areas to grow your expertise

Since the release of the Hackitt Report, and the subsequent regulations for multi-occupancy residential buildings, as on-site paint application specialists, we often receive questions about the effectiveness of intumescent paint coatings and exactly how they work.

Our team came together to share our expertise on how intumescent paint provides significant fire protection, and the key areas to be aware of when working with this system on any future projects.

What is an intumescent paint coating?

Intumescent paint coatings are an important form of passive fire protection which can be applied to a variety of building materials, and is most commonly applied to structural and load-bearing steel. When exposed to high temperatures, the reactive paint swells up by creating lots of small bubbles, acting as a thermally insulating layer. This reaction reduces the time it takes for the materials to reach their critical failure temperature, providing building users with more – and potentially lifesaving – time to evacuate the building.

The critical role of volume and thickness

Critical to the effectiveness of the coating, the volume and thickness of the paint required are unique to each project and specified prior to application. The specification is dependent on certain factors, including the fire protection requirements and the substrate in question. As with all industrial coatings, the thickness of intumescent paint applied is measured in ‘microns’.

Understanding the difference between ‘wet film thickness’ and ‘dry film thickness’

A key part of the application process involves ensuring the paint is applied consistently across the full surface, according to specification. There are two measures which are frequently taken in order to achieve this, they are referred to as ‘wet film thickness’ (WFT) and ‘dry film thickness’ (DFT).

The wet film thickness should be frequently measured during application using a wet film gauge. This is a plastic or metal comb-like card which has graduated teeth on its edges to measure the number of microns applied.

Dry film thickness is used to verify the paint coating after application and drying. It is measured using an electronic dry film testing gauge and can be used by applicators, manufacturers, or external assessors.

Understanding fire rating requirements

It is important to know what fire rating is required prior to any application. This is usually determined by a number of minutes of fire protection required, for example, 30, 60, 90 or 120 minutes. The minute specification represents the additional time it would take for the substrate to reach its critical failure temperature in the event of a fire, and therefore the additional escape time for the building users.

The higher the number of minutes, the thicker the coating required. The fire rating required is usually specified by the architect, building control, or fire engineer on the project.

Understanding the nature and condition of the substrate

Understanding the nature and condition of the substrate prior to application is a crucial factor in diagnosing the preparation work required before we can even think about applying paint. Some of the factors we would consider include, but are not limited to, the material composition, the age, any previous paint coatings or treatments and any corrosion.

Determining the best specification for the type of steel

Steel beams come in various shapes and sizes. Having a prior knowledge of whether we are working with open sections, such as universal beams and columns, or closed sections, such as circular and square hollow sections, is vital information required for an accurate specification. Due to their compositions, each one has different requirements when it comes to achieving the same level of fire protection. This detail determines the most appropriate products, as well as the volume and thickness required for effective fire protection.

Environmental considerations of a project

Just like other spray painting services, environmental factors affect the application of intumescent paint coatings. Considerations for this must be made when it comes to both the application process, and the type of product specified.

As you would expect, intumescent paint cannot be applied in the rain; but aside from the obvious, other factors such as heat and humidity can also affect a successful application. With each specification, there are strict drying and curing times as well as guidance on temperature parameters. It is crucial that these instructions are adhered to, to allow the coating to perform effectively.

Taking into account the long-term environmental conditions of the project is also an important consideration in selecting the correct product. These considerations could include whether the substrate is internal or external and whether it is directly exposed to rain and the elements, for example, projects close to a coastline may even be affected by the salty air. Every one of these factors influences the product specification.

A lack of regulation

Our managing director, Jo Thornicroft, was recently featured in Building Design, where she speaks about the role of intumescent paint in fire safety and why a regulatory body is needed. The lack of governance surrounding intumescent paint application has long been an issue, and it’s vital that this significant system in fire safety is no longer overlooked.

Are you looking for a qualified and experienced intumescent paint specialist? Get in touch with us:

Alternatively, give us a call: 0161 928 8193

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