A Guide To Intumescent Paint

In this guide, we will discuss how intumescent paints work, and what materials they are designed to protect.

How Does Intumescent Paint Work?

Endothermic reactions enable intumescent paints to protect surfaces. They absorb heat from the surrounding environment and undergo a chemical transformation in which they rapidly expand (the Latin word “tumesco” from which intumescent derives, actually means “to swell”). A thin-film coating of intumescent paint will expand at a rate of 50:1, while a thick-film coating will expand at a rate of 5:1, as a general rule. This expansion results in a microporous carbonaceous foam that effectively reduces the heat transfer rate between the fire and the underlying surface.

Time and Heat Limits of Intumescent Paint

Intumescent paints are rated according to their ability to withstand temperatures of more than 250°C, which is the approximate temperature at which endothermic reactions occur.

Paints are usually classified as 30, 60, 90, or 120 minutes – these durations represent the longest periods during which the paint can provide competent passive fireproofing against high heat. The paint you choose is determined by the intended use.

What Materials are Protected by Intumescent Paint and Cementitious Coatings?

Intumescent paint can be used to safeguard materials like steel. There are other coatings that you can apply to materials like concrete such as cementitious coatings.

Cementitious coatings are comparable to intumescent coatings, however, they do not produce black smoke, char, or expand when exposed to fire. Cementitious coatings are quite inexpensive and are extremely durable at withstanding very high temperatures.

Here are some of the applications for these coatings:

Steel

Steel has a melting temperature ranging from 350°C to 750°C. Its nominal tensile strength and load-bearing capacity significantly diminish at this temperature, posing an increased risk of structural collapse. Intumescent paint can be used on a variety of steel components to extend the time it takes to reach the critical temperature. Beams, columns, brackets, and studs are all examples of such elements.

Spraying is the most effective method for applying intumescent paint to steel structures. It can be used as a base layer on top of the steel itself or over a compatible anti-corrosion primer. For aesthetic reasons, it’s also possible to add a second coat of paint, but only if it’s authorised for use with the intumescent coating.

Concrete

Cementitious coatings are sprayed on concrete to prevent the destructive effects of fire and preserve the building’s structural integrity. Cementitious coating is created by combining it with water in a uniform slurry to be sprayed at a nozzle directly onto the concrete. This enables complete coverage of all concealed holes.

Intumescent paint, when used in residential or commercial buildings, improves the passive fire protection of a building. It aids in the preservation of a structure by delaying heat transfer from fires to internal structures (of varying materials).

For further information on intumescent paint, or if you are looking for the application of intumescent paint to your structure, please get in touch with the experts at Ark Fire Protection today.