Thick-Type Fire-Retardant Coating (Non-Intumescent)

The coating thickness ranges from 8mm to 50mm, with a fire resistance rating of 0.5 to 3 hours. In a fire, the coating does not expand. Its flame-retardant performance relies on non-combustibility, heat absorption, and low thermal conductivity to delay the steel's temperature rise. Because most additives are inorganic, the cost is low. It is usually applied via spraying for indoor structures requiring more than 2 hours of fire resistance, though its decorative properties are poor due to the thickness.

Thickness Standards at a Glance:

• Ultra-thin: ≤3mm

• Thin-film: ＞3mm and ≤7mm

• Thick-type: > 7mm and ≤50mm.

Thin-Film Fire-Retardant Coating

Thickness ranges from 3mm to 7mm, with fire resistance not exceeding 2 hours. When exposed to fire, it expands and foams to form a heat-insulating layer. The base material is usually a latex polymer (such as styrene-modified acrylic, polyvinyl acetate, or vinylidene chloride emulsion) mixed with flame retardants. It consists of a base layer (insulation) and a top layer (decoration), offering better aesthetics than thick coatings.

Ultra-Thin Fire-Retardant Coating

A newer variety with a thickness not exceeding 3mm. It also expands and foams into a dense insulating layer under fire. It can be applied by spraying, brushing, or roller coating. It is highly favored for exposed steel structures due to its fine viscosity, thin profile, and superior decorative finish.

New Standards (GB 14907-2018 & GB 51249-2017)

The 7mm boundary exists in older regulations. Under new rules:

1. Ultra-thin: Generally for ratings < 1.5h (Actual products are often around 2mm).

2. Thin-film: Ratings up to 2 hours (Actual products are often around 5mm).

3. Thick-type: Required for any fire resistance rating exceeding 2 hours.

Example Thickness (Based on manufacturer test reports):

• 2.0h rating:4.8mm±0.2mm

• 1.5h rating:3.2mm±0.2mm

• 1.0h rating:2.3mm±0.2mm

Construction Methods

1. Substrate Treatment: Remove dust, oil, and rust. Apply an alkali-resistant anti-rust primer.

2. Reinforcement: For steel widths over 300mm (H-beams/Rectangular steel), metal mesh (steel plate mesh) must be fixed with welded rods or insulation nails before coating.

3. Application:

• First Layer: Mix with 3% matching glue and water. Spray at a thickness < 5mm.

• Subsequent Layers: Apply when the previous layer is 70–80% dry (approx. 24h). Each subsequent layer can be 8–10mm thick until the design thickness is reached.

• Surface Finish: Do not smooth between layers; keep the surface rough (pockmarked) to improve adhesion for the next layer.

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