Intumescent coatings are coatings applied to surfaces which offer additional fire protection due to their inherent properties. They are designed to swell or expand in thickness when exposed to fire. This provides an insulating, foam-like protective barrier against the extreme heat generated in building or structural fires. They are not “fireproof”, but they are designed to give additional protection and time in a fire emergency.
These coatings are often used on steel beams and supports, pipes and other steel building materials. Obviously steel does not burn. However it can lose some of its structural integrity when exposed to extreme heat for long periods such as those conditions experienced in a building fire. Their use is not limited to steel structures, however, as they may be applied to wood and other materials, such as doors which need additional fire ratings.
The coating’s effectiveness comes from the expansion of the coating itself. Depending upon the product, the intumescent coating may expand as much as 30 times it’s normal thickness (or even more). This allows the coating surface to char, while protecting the coated surface underneath. This charring, and the subsequent creation of ash layers, can be repeated several times, which also aids in insulating the substrate from the extremes of heat. To increase the effectiveness in certain applications, a mesh reinforcement may be laid on or around the coated surface, which helps to retain the char layer.
The proper application of intumescent coatings is essential to maximizing their effectiveness. Their application is generally thicker than many coatings (anywhere from 30 to 500 mils) and the surface to which they are applied must be properly prepared and primed. They are most often used by industrial painting contractors in new construction; however they are also quite commonly used to upgrade older facilities. As part of a retrofit they can be applied in existing facilities, giving them additional fire safety and peace of mind.
While more expensive than standard coatings, the added benefits and protection make them worth the investment.