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Fire-retardant coating is a special type of coating used on the surface of flammable substrates; it reduces the flammability of the coated material’s surface, prevents the rapid spread of fire, and helps to increase the fire resistance rating of the coated material. Fireproof coatings possess flame-retardant or non-flammable properties, which prevent the protected substrate from coming into direct contact with air, thereby delaying the ignition of the material and reducing the speed of combustion. It also has a low thermal conductivity, which can delay the transfer of flame temperature to the protected substrate. When heated, fire-resistant coatings decompose to release non-flammable inert gases, which dilute the flammable gases produced by the heating of the object being protected, thereby making it harder for those gases to catch fire or slowing down their combustion rate. Nitrogen-containing fire-retardant coatings decompose when heated, releasing groups such as NO and NH3, which combine with organic free radicals to interrupt the chain reaction and lower the temperature. Expansive fireproof coatings expand and foam when heated, forming a carbonaceous foam insulation layer that encloses the object to be protected, delaying the transfer of heat to the substrate and preventing the object from catching fire or experiencing a decrease in strength due to rising temperatures. The basic components of thick-coated fireproof coatings for steel structures are: binders (silicate cement, magnesium chloroxide, or inorganic high-temperature binders, etc.), aggregates (expanded vermiculite, expanded perlite, aluminum silicate fibers, mineral wool, rock wool, etc.), chemical additives (modifiers, hardeners, waterproofing agents, etc.), and water. The binders for fire-resistant coatings on steel structures include portland cement, magnesium oxychloride cement, and inorganic binders; common inorganic binders include alkali metal silicates as well as phosphates and other substances. Non-expanding fireproof coatings are primarily used for providing fire protection to materials such as wood and fiberboard, and they are applied to the surfaces of wooden structural frames, ceilings, doors, and windows. Expansive fireproof coatings include non-toxic expansive fireproof coatings, emulsion-type expansive fireproof coatings, and solvent-based expansive fireproof coatings. Non-toxic intumescent fireproof coatings can be used as fireproof coatings or fireproof putties to protect cables, polyethylene pipes, and insulating boards. Emulsion-type intumescent fireproof coatings and solvent-type intumescent fireproof coatings can be used for fire protection in buildings, power systems, and cables. Classified structural fireproof coatings are those used on steel structures, concrete structures, and wooden structures as fireproofing materials; they serve primarily as protective layers for non-combustible components. These fireproof coatings have thick layers, low density, and a low thermal conductivity, giving them excellent heat-insulating properties. Finish-type fire-retardant coatings are generally used as protective materials for combustible substrates, such as on wood, the surfaces of household appliances, the fire-resistant layers on cables, and the surfaces of other decorative materials; they possess both decorative properties and fire-retardant capabilities. When purchasing fireproof coatings, it is necessary to check their fire-resistant properties; the fire resistance of the coating should be tested at the time of purchase. When exposed to intense fire, intumescent fireproof coatings expand significantly by forming bubbles, with protrusions appearing on their surface; they do not suffer any damage within a few minutes. In contrast, fake and inferior fireproof coatings hardly produce any bubbles, and large amounts of debris fall off from them, while the wooden substrate burns and gets damaged very quickly. The combustion performance of fireproof coatings is determined in accordance with **standards**; in addition to meeting the requirements regarding fire resistance, such coatings are classified as grade 1 or grade 2 based on their combustion properties. Under the specified experimental conditions, the flame resistance time of Class 1 fireproof coatings shall be no less than 20 minutes, and the heat resistance time of Class 2 fireproof coatings shall be no less than 10 minutes. Users should pay attention to making the distinction when choosing, to avoid companies passing off inferior products as good ones. When purchasing products, avoid seeking cheap options. Currently, domestic companies produce fireproof coatings with a fire resistance rating of level 2, and the cost of such coatings is above 8,000 yuan per ton; if the selling price is lower than this, the quality is likely to be questionable. Therefore, one should not seek cheap options when making a purchase, otherwise low-quality and environmentally unsound products may be acquired as a result. Check the certification documents and select the brand. At present, a system of type approval for fire protection products is in place for such products; fire protection coatings sold on the market must possess a **type approval certificate for fire protection products as well as a report confirming successful type testing. In addition to checking whether the product comes with a complete **inspection certificate**, choosing brand products with a proven reputation can enhance fire safety at home. Key points for applying fireproof coatings: 1. Scraping method – Metal or non-metallic scrapers such as rubber sheets, fiberglass scrapers, or horn scrapers are used to apply the coating manually; this method is suitable for applying various types of thick paste-based fireproof coatings and putties. 2. In the roller coating method, the roller is a hollow cylinder with a relatively small diameter; its surface is covered with long fibers made of synthetic materials. There are two washers at each end of the cylinder, and a hole is present in its center through which the curved handle passes. To use it, the roller is first dipped into the paint to get it saturated, and then it is used to apply the paint to the desired surface with force. Currently, roller coating systems that use air compressors to deliver paint are being developed. 3. Brushing method: The brushing method is suitable for applying coatings to objects of any shape, and the vast majority of fire-resistant coatings can be applied using this method. The brushing method can easily penetrate into the pores of the metal surface, thereby enhancing adhesion to it. The disadvantages are low production efficiency and high labor intensity; sometimes brush marks remain on the coating surface, affecting its aesthetic appearance. 4. The spraying method is a construction technique that uses compressed air and a spray gun to atomize the paint; it is characterized by a uniform quality of the coating obtained after spraying, as well as high production efficiency. The disadvantage is that some of the paint is lost, and at the same time, the extensive evaporation of solvents affects the operator’s health. Method of applying fire-resistant coating to steel structures (1) Before application, the steel components must be thoroughly rust-removed; it is advisable to apply an anti-rust paint as well, to prevent new rust from forming before the fire-resistant coating is sprayed. Dust on the surface should also be removed prior to spraying. (2) The temperature of the painting environment should be maintained above 0°C, with no drafts. (3) Use a spraying equipment for application; the thickness of each coating layer should be 5–10 mm, with applications made every 2–8 hours until the desired thickness is achieved. Local repairs can be carried out by hand applying the coating. (4) The coating is two-component; before spraying, the component A and component B must be mixed evenly according to the specified ratio. During preparation, first pour the liquid material into the mixer and stir for 3–5 minutes, then add the powdered material; for a quantity of 20–26 kg, stir until the desired consistency is achieved, after which it can be used for spraying. When applying this type of two-component paint, it should be noted that it cures rapidly after mixing; therefore, the mixing time should be kept within 10 minutes, and spraying should be completed within 20 minutes after mixing. In hot summer weather, a faster pace is advisable. (5) Ensure proper curing and maintenance. The freshly applied coating should be protected from rain, and it will cure within 48 to 96 hours at room temperature. (6) The coating should be stored at 4–40°C; it must not be stored outdoors or exposed to the sun. The paint is valid for half a year. What are fire-resistant materials? Fire-resistant panels, fire doors, fire-resistant wooden window frames, fire shutters, fire-resistant coatings, fire-resistant glass, fire-resistant storage containers, fire-resistant insect-proof wood, fire-sealing materials, fireproof bags, fire-resistant plastic materials