How Intumescent Paint Works

Intumescent paint – what is it and how does it work? Intumescent paint is used as a passive form of fire protection. How intumescent paint works is quite simple. The paint is applied to the surface of a material, and when exposed to heat, the paint expands, increasing in volume and decreasing in density. This change in volume and density makes the intumescent paint a poor conductor of heat. Without the conduction of heat, the fire doesn’t spread as quickly, potentially offering more time for occupants to evacuate and response teams to mitigate damage to the building.


How intumescent paint works depends on the type of intumescent paint used during construction. There are two general types of intumescent paint used, depending on where on the building the paint is being applied: a soft char and a hard char. ShieldAll 6023-Fire Guard is a soft char intumescent.

Soft Char Intumescent

A soft char intumescent paint is often used on interior structural and finished surfaces. When heated, these intumescent paints cause a light char to form and result in poor heat conduction, retarding the heat transfer of the fire. The main components of the intumescent paint react with one another causing a carbonaceous foam to form. This foam often contains hydrates that, when heated, release water vapors. These water vapors create a cooling effect, further retarding the progression of the fire. Once the water has been expelled, the remaining insulation properties of the intumescent paint continue to slow the heat transfer process.


Hard Char Intumescent

Another form of intumescent paint is a hard char intumescent paint. Whereas a soft char will expand into a foam-like substance to insulate surfaces from heat, a hard char will expand into a solid barrier, creating a firewall that impedes the spread of fire and smoke. Hard char intumescents tend to be pricier and harder to work with.


You might use a soft char intumescent like ShieldAll 6023-Fire Guard in an attic to help slow the spread of fire over a surface. A hard char intumescent you would almost exclusively use in plastic pipes or in vents. Their hard char acts to close the pipe (often at intersections) or vent and slow fire and smoke spread. 


ShieldAll 6023-Fire Guard protects interior surfaces and slows the growth of flame and smoke using its intumescent properties. Tested using the industry-standard ASTM E-84 measurement, ShieldAll 6023-Fire Guard produces a Superior rating and is a Class-A fire retardant.

Choose ShieldAll 6023-Fire Guard, the best solution for a strong foundation!



Call  for Volume Pricing  with Significant Discounts

Sales: (507) 722-1562