Discussions about intumescent coatings are a common occurrence in commercial construction circles when a unique solution is required for achieving and maintaining excellent fire-rating standards for building codes.

Mastics and intumescent paint are common coating technologies that utilize the formation of char to prevent fire from spreading. Intumescent coatings expand over one hundred times their thickness upon the exposure to the fire’s heat, allowing the coating to fully activate within the temperatures of 300 to 400 degrees Fahrenheit. Architects utilize these coatings to expose a building’s structure when a building code fire protection evaluation is required.

Heat Resistant Coatings

When the flame resistant coatings are heated to their full capacity, carbon foam expands and resists transferable heat. Graphite (pure carbon) is high in heat density and is very difficult to obtain a temperature increase. The fire resistant coatings expand as a non-combustible material when exposed to fire. Oxygen is absorbed by the coatings, which acts as a fire detour-ant for the substrate, which creates a less combustible environment. In the occurrence of a fire, the substrate found beneath the Intumescent paint has been found to be salvageable and may be re-painted. Intumescent paints differ from Intumescent mastics and obtain minute fire ratings. Intumescent paint and mastics are applied with a technique similar to rolling or brushing household paint. However, most manufactures recommend a spray application for optimal coating results.

Intumescent Mastics

Intumescent mastics provide optimal fire ratings within 45 minutes up to two hours and are trowel-applied in ranges of 1/8 inch to 3/8 inch thickness. Laboratory underwriters have divided the building material coatings into two categories, “general purpose” and “fire retardant”. In order for the coating to receive the “fire retardant” category, it must show a significant reduction of flames found in tested materials such as Douglas fir trees and other interior substrates. The tested materials have to show a 50 percent flame reduction for the product to qualify for the superior ratings.

Coating Application

When an architect implements certain details within a structure, it is extremely important to allow all adjacent spaces to remain clear of additional connections or materials to allow the coatings to reach their full expansion capacity. It is equally important to refrain from top-coating the product with paint, which may prevent the occurrence of the chemical reaction. The chemical reaction is necessary to deter a fire.

In prior years, the fire resistant coatings were found to be sensitive to moisture. This issue required applications of the substance. Modern technology has turned over a new leaf in the development of these quality coatings providing lasting durability for years to come. Surface preparation is required prior to the application of this material. It is important to follow the application guidelines as specified by the product’s manufacturer.