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I. Pre-construction Preparation

II. Construction Steps

● Coating Application

● Coating Mixing

● Coating Treatment

I. Pre-construction Preparation

Material Preparation
Check the quality and quantity of the required materials to ensure they meet the engineering requirements. Ultra-thin fire-retardant coating mainly consists of fire-resistant particles, thinner, etc. The coating quantity should be reasonably calculated based on the construction area and thickness requirements. The qualified coating should be stored in a dry and well-ventilated warehouse, neatly arranged, and protected from wind, rain, and direct sunlight. Coating that has clumped or deteriorated should not be used. Meanwhile, check the steel structure surface for any missing rust-preventive primer and make timely repairs. Before use, the substrate to be coated should be cleaned of oil, dust, and checked for compatibility between the rust-preventive paint and the fire-retardant coating on the substrate surface. Once opened, the ultra-thin steel structure fire-retardant coating should be used up in one go; any unused coating should be resealed tightly.

Equipment Preparation
Ensure the completeness of all equipment required for construction (such as coating mixers, scrapers, brushes, spray guns, etc.) and carry out necessary maintenance and repairs. Before use, check that the equipment is operating normally.

II. Construction Steps

Substrate Preparation
Clean the substrate surface to remove dust and dirt.
Repair cracks and dents on the substrate surface.
Use a primer to treat the substrate to increase the adhesion of the coating. For steel structures, according to the regulations of the steel structure fire-retardant coating construction scheme, the substrate surface should be derusted and rust-prevented before construction, seeking comprehensiveness and thoroughness; the substrate surface should also be cleaned of dust, oil, and other impurities, which can be done using high-pressure gas or a high-pressure water gun for surface dust removal. The fire-retardant coating can be applied only after the substrate surface is inspected and found to be free of water, dust, debris, oil, and other contaminants. Before construction, the supporting components' surfaces should be cleaned (including derusting, removing welding slag, and other contaminants).

Coating Application

Coating Mixing

Mixing the coating evenly is a critical step to ensure coating quality. When using a mixer, the coating bucket should be sealed well to prevent coating volatilization and solidification; the mixing time should generally not be too long to avoid excessive coating dilution.

Coating Application Methods
Brush Application: Use a brush to evenly apply the coating onto the substrate, ensuring uniform coating thickness and avoiding missed or excessive application.
Spray Application: Use a spray gun to evenly spray the coating onto the substrate. When spraying, maintain an appropriate spray gun distance and spray pressure to ensure coating uniformity. Ultra-thin steel structure fire-retardant coating can also be applied by spraying. The coating should be fully mixed before application. The first coat should be applied with a thickness of 0.10 - 0.15mm. After the surface is dry (18 - 24 hours later), apply the second coat with a thickness of 0.20 - 0.25mm. For subsequent coats, the coating thickness should be controlled at around 0.25 - 0.3mm until the specified thickness is reached. The time interval between each application should be 18 - 24 hours or more. The construction environment temperature should be 0 - 40°C, the substrate temperature should be 5 - 45°C, the relative humidity of the air should not exceed 90%, and the construction site should have good air circulation with a wind speed not exceeding 5m/s. Outdoor work or construction when the surface of the components is dew-covered is not advisable. In addition, when spraying the bottom layer, to improve the bonding strength between the coating and the steel beam substrate, a small amount of water-based adhesive (usually 0.4Kg/M2 or as per the product instructions) should be added to the bottom slurry, with a spray thickness of about 5mm. After the surface of the bottom coating dries (24 hours after the bottom coating application), the surface coating can be sprayed with a thickness of 10mm. For obvious unevenness, use a spatula to smooth the surface to ensure a uniform and glossy coating surface. Before spraying, conduct a test spray and make a sample to determine the optimal parameters for spray pressure, spray distance, and spray gun movement speed through the test spray. After comparison and confirmation by the supervisor with the standard sample, large-area spraying can be carried out. During the spraying process, the mixing of materials and the feeding into the spraying machine should be continuous and not paused.

Coating Thickness Control
Common methods for controlling coating thickness include using a scraper or brush to measure the coating thickness and calculating the theoretical coating thickness based on the coating's covering power and construction area.

Coating Treatment

Coating Curing: After coating application, curing treatment is required, which generally takes some time.
Coating Inspection:

Inspect the coating to ensure that the coating surface has no obvious defects.
Coating Cleaning:

Clean the coating surface to remove dirt and impurities.

Coating Repair: Repair any damage to the coating surface.