what is intumescent paint?
Often called fire retardants, or mistaknely called "fireproof" paints, Intumescent paints refer to that class of specially designed paints which swell and form a protective "char" as a result of extreme heat exposure - such as a fire - increasing in volume. This char is a poor conductor of heat, which benefits the steel it is applied to, as it protects the surface for an increased time from the destruction fire may otherwise cause.
Typically intumescept paints are applied to structural steel, for the purposes of ensuring that in the case of a fire, the steel does not warp as quickly as it may otherwise, thus allowing fire crews to extinguish the flames.
For an intumescent to function properly, it relies on the interaction of three specific components which it is made up of. The 3 components are:
- Carbon Supplier: Polyols as starch or pentaerythritol
- Acid Source: Ammonium polyphosphate
- Expanding Agent: Melamine
Intumescent paints are supplied and applied in one of two forms - solvent or waterborne polymeric binders. Due to the negative impact solvent based products have on the environment, Remedial Building Services Australia uses water based intumescents which are less hazardous, more stable and better for the environment. However, at times, other components are added to improve the paint properties and enable easy application, enhance build and achieve faster drying.
the 4 stage intumescent process
 |
- The heat from the fire begins to soften the polymeric binder inside the fire retardant paint.
- The heat also causes a release of an organic acid (from the Ammonia Polyphosphate)
|
 |
- Carbonisation of the polyols begins to take place
|
 |
- Gas produced through the decomposition of the blowing agent (melamine), swelling the molten mixture.
|
 |
- The final stage is solidification of the foamed char, through a cross-linking reaction, to maintain the insulation.
|
For further information on the intumescent process, please refer to a referenced source.
