Fire-resistant coatings for steel structures are primarily used to protect steel structures, enhance their fire resistance, and increase their fire strength. However, there are differences among fire-resistant coatings for steel structures, which are categorized into thick and thin types based on varying requirements. The selection of these two types of fire-resistant coatings also involves specific considerations.

Thick-type Steel Structure Fire Retardant Coating: Thick-type steel structure fire retardant coatings typically refer to coatings with a thickness of 5-50mm, where the thicker the coating, the higher the fire resistance. When combined with some reinforcing materials, this type of coating delivers a very satisfactory effect.

During fires, the coating does not expand, relying on the non-flammability of the material, its low thermal conductivity, or the heat-absorbing properties of the materials within the coating, to delay the heating of the steel and protect the steelwork.

Due to the fact that the additives in thick steel structural fire-resistant coatings are typically inorganic materials, the cost is low and the cost-performance ratio is high. Moreover, the application method uses spraying, which is disadvantageous in that it can be too thick and affect aesthetics.

Thinner Steel Structural Fire Retardant Coating: As the name implies, this is the counterpart to thicker coatings. These coatings typically range from 3-7mm in thickness, using suitable latex polymers as the base material, combined with flame retardants and additives.

For this type of fire retardant lacquer, the selected emulsion polymer must have good adhesion, durability, and water resistance to the steel substrate. Common emulsion polymers used as bases for this type of fire retardant lacquer include styrene-modified acrylic emulsion, polyvinyl acetate emulsion, and chlorinated polyvinyl chloride emulsion, among others.

For fire-retardant coatings with aqueous emulsion as the base, flame-retardant additives, pigments, and fillers are dispersed in water, making water function as the dispersing medium. To better disperse the granular additives, dispersants such as sodium hexametaphosphate, commonly used, are also added.

The coating is typically divided into a base layer and a topcoat, offering superior decorative qualities compared to thick-coat types. It is applied by spraying and is commonly used on steel structures in buildings with fire resistance requirements not exceeding 2 hours.