The environment with humidity as high as 80% in rainy season will accelerate metal corrosion, and rust spots can appear when ordinary nails are exposed for 3 days. Based on the latest industry standards and construction measured data, this paper analyzes the performance comparison of five types of antirust coatings and the golden rule of rainy season construction to help you avoid 90% rust risk.
First, the core index analysis of antirust coating
Attention should be paid to coating selection in rainy season:
Water resistance: the decline rate of adhesion after soaking for 72 hours is ≤5%.
Drying speed: surface drying time ≤30 minutes (under the condition of humidity 80%)
Environmental protection: VOC emission ≤100g/L (national standard level I).
Performance Comparison of Class II and Class V Antirust Coatings
1. Waterborne acrylic antirust paint
Advantages: fast drying (20 minutes clock drying), environmental protection and tasteless, suitable for indoor use.
Limitation: Weathering resistance is weak, and it needs to be reapplied every 2 years.
Applicable scenes: plasterboard ceiling self-tapping nails, wooden structure.
2. Epoxy zinc-rich primer
Advantages: Zinc powder content ≥80%, and the cathodic protection effect is remarkable.
Key points of construction: it is necessary to cooperate with epoxy micaceous iron intermediate paint to enhance the sealing performance.
Measured data: salt spray test for 1500 hours without corrosion.
3. Oily alkyd antirust paint
Advantages: Single-layer protection cycle is 3-5 years, with high cost performance.
Limitation: VOC emission is high, so forced ventilation is needed.
4. Nano anticorrosive coating
Characteristics: superhydrophobic surface, contact angle > 150.
Experimental data: it has no infiltration after soaking for 30 days, and is suitable for long-term rain soaking environment.
5. Pre-coating of self-tapping nails
Recommended model: C4 coating of engraved seal.
Advantages: it still has self-repairing ability after mechanical damage.
Three golden rules for rainy season construction
Pretreatment key:
-The nail surface is sanded to Sa2.5 level.
-wipe with alcohol to remove oil stains (drying is required when the humidity is higher than 75%)
Coating construction skills:
-"Bo Tu multiple pass" process is adopted, and the thickness of each layer is 30-50μm m.
-The pressure of the spray gun is 0.4-0.6MPa, and the spray gun moves at a constant speed 20cm away from the surface.
Environmental control:
-Avoid construction for 6 hours before and after rain.
-The temperature of the substrate should be above 3℃ above the dew point.
Precautions: After construction in rainy season, rust detector is needed to verify the coating integrity. Mastering these technical points can prolong the service life of nails by 5-8 times!
