Review on intumescent coatings

PIN compounds are essential to intumescents, used to protect structures (steel, concrete, wood) and cables from fire. Comprehensive review of published research found over 13 000 papers on intumescent coatings, of which over 600 were analysed and over 200 finally selected for review (most dating since 2010). The review covers different types of intumescent, their production and application, use on and interactions with different substrates. Intumescents are based on an acid source (releasing acid to generate char in fire), a carbonaceous char source, a blowing agent (releasing gas to generate the intumescent foam), binders and other additives (pigments, thickeners, additives to facilitate application …). Phosphorus PIN compounds are key as acid sources, removing water molecules from the carbon source to generate stable, protective char. Phosphorus compounds also provide fire resistance, improve adhesion and reduce corrosion. The blowing or foaming agent must release gas or expand at the intended temperature, and urea, guanidine, melamine or expanded graphite are widely used. Uses of intumescents to protect structural steel, timber and concrete are discussed. Challenges for intumescents include improving chemical formulation to prolong fire protection times, reducing manufacturing complexity avoiding initial fire spread, reducing smoke toxicity, weathering durability, application to concrete, plastics …

“A Comprehensive Review on Intumescent Coatings: Formulation, Manufacturing Methods, Research Development, and Issues”. T. Nazrun et al., Fire 2025, 8, 155 https://doi.org/10.3390/fire8040155