Thick-coating fire-resistant steel structural coatings refer to coatings with a thickness greater than 3mm and less than or equal to 7mm, offering certain decorative effects. They expand and thicken under high temperatures and provide fire resistance to steel structures for up to 2 hours. Typically, these coatings are made from suitable water-based polymers as the base material, combined with flame-retardant composite systems, fire retardants, and refractory fibers, sharing the same fire-resistant principle as ultra-thin coatings. For such fire-resistant coatings, the required water-based polymers must have good adhesion, durability, and waterproof properties with the steel base material. Their decorative performance is superior to that of thick fire-resistant coatings but inferior to ultra-thin steel structural fire-resistant coatings, generally with a fire resistance limit of less than 2 hours. Therefore, they are commonly used in fire-resistant steel construction projects with fire resistance performance less than 2 hours, often applied via spraying. Over time, a significant portion of the market has been replaced, but with the emergence of ultra-thin steel structural fire-resistant coatings, its market share has gradually been eroded.