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In terms of fire retardant coatings, the two most popular options are intumescent coatings and cement coatings.
Each coating has its own advantages-intumescent coatings are very effective but also relatively expensive, while cement coatings are easier to meet your budget, but there are some specific shortcomings, which we will introduce below.
Let us understand each type of coating in detail, list the specific advantages and disadvantages of each coating one by one, and discuss the best application of each coating.
What are intumescent and cement-based coatings?
Intumescent coatings will swell when exposed to fire to protect and insulate their substrates.
It works like this: The intumescent coating consists of a chemical mixture suspended in a binder. When it is exposed to the heat of a fire, the adhesive will melt and begin a chemical reaction. This chemical reaction produces foam, and the previously thin intumescent coating begins to expand rapidly, usually 25-50 times thicker.
This chemical foam protects the substrate from fire damage; when applied to steel, it prevents buckling of the steel even at high temperatures.
Cement coating is simpler. These are basically coatings mixed with lightweight cement. Traditional concrete is very fire-resistant-and inexpensive; but due to its weight, it is impractical as a general fire-resistant measure, which requires heavy steel support.
On the other hand, cement coatings provide you with all the fire resistance of concrete while being light in weight. They are also quite cheap, especially when compared to intumescent coatings.
So what is the problem? Well, just like traditional concrete, their application is very laborious. They require a lot of surface preparation, followed by a few coats.
That's not all; when the cement coating dries, it will slightly separate from the substrate. If moisture accumulates in this space, as often happens in humid environments, it will corrode the surface that the cement coating should protect.
Let us investigate the advantages and disadvantages of each coating.
When you look at the functions that each coating must provide, it is clear that there is no one-size-fits-all solution. The best coating for you will depend on your unique situation. Having said that, let's talk about the ideal application of each coating.
Intumescent coatings perform well in highly visible environments because intumescent coatings look as attractive as fine traditional coatings, and if topcoats are used, they can even be as attractive as top epoxy resins. They are also ideal for high humidity environments because they adhere tightly to the substrate and lock in moisture.
They are also very suitable for mild or climate controlled environments. However, local factors during application, such as humidity, temperature, and dew point, are important factors that affect the adhesion of the coating to the substrate (or how far).
Cementitious coatings are ideal for dry environments where moisture accumulation is not a problem. They are also suitable for surfaces that are not regularly observed, such as underwater structures, roof structures or highway structures.
Please note that whenever a structural fire protection coating is selected, facility managers need to consider NFPA and IBC guidelines as well as local guidelines.
Although both coatings provide very effective fire resistance, intumescent coatings are more versatile, look more beautiful and more advanced.
Having said that, in environments that require minimal fire protection, limited budgets, or aesthetics, cement coatings are a completely acceptable alternative.
Remember, no matter what choice you make, facility managers need to follow IBC and NFPA standards when determining fire protection measures. For safety reasons, it is best to consult a professional coating expert to ensure that you fully meet the requirements.
Tommy O'Shaughnessy is the owner of CDN Paint, an online platform that connects owners, facility managers and engineers with top paint professionals.