Intumescent paint explained
Intumescent coatings swell into an insulating char when exposed to heat, buying time for a structure in a fire. They are a specified, measured product — not a decorative choice.
How the system works
Under heat, the coating expands many times its applied thickness and forms a char layer that slows heat transfer into the steel below, protecting its load-bearing capacity for a defined period.
Film thickness is the specification
Protection is a function of dry film thickness against the section factor of the steel. Applied thickness is measured and recorded — this is the part that distinguishes a compliant job from a decorative one.
Primers and topcoats
Intumescent systems sit on a compatible primer and are usually finished with a decorative sealer coat. Mixing incompatible products can compromise the whole system.
Documentation
Specifiers should expect product data, applied thickness records and confirmation that the system matches the required fire rating for the element.
Common questions
Can any painter apply intumescent coatings?
It needs the right products, equipment and measured application with records — it isn't a standard decorating task.
Does intumescent paint have to be a certain colour?
The base system is finished with a compatible topcoat, so a wide range of colours is achievable.
How is thickness verified?
With a wet and dry film thickness gauge, recorded against the specified requirement.
Can existing painted steel be coated?
Only after the existing coating is assessed for compatibility and adhesion — sometimes it must be removed.
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Next step
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