The leveling property of water-based steel structure paint directly affects the uniformity and gloss of the paint film. Poor leveling can easily result in orange peel, brush marks, or a grainy texture on the paint film surface, reducing protective performance and aesthetics. Improving this requires a comprehensive approach involving three aspects: paint formulation optimization, application process adjustment, and environmental control, forming a systematic solution.
The paint formulation is the foundation of leveling property. The selection and dosage of leveling agents are crucial. Silicone-based leveling agents can reduce the surface tension of the paint, allowing it to spread evenly on the substrate surface, while acrylic-based leveling agents can extend the leveling time and prevent premature curing. It is generally recommended that the leveling agent addition be 0.1%-1% of the total paint volume, but the optimal ratio needs to be determined experimentally. Furthermore, the paint viscosity must be controlled within a reasonable range. Excessive viscosity leads to poor flowability and difficulty in leveling; excessively low viscosity easily causes sagging. Viscosity can be adjusted using thickeners (such as cellulose ethers) or thinners (such as water or co-solvents). Generally, a viscosity of 20-60 seconds when measured with a Ford cup (4 cup) is ideal. The dispersibility of pigments and fillers is equally important. If pigments and fillers aggregate and form particles, it will damage the smoothness of the paint film. Pre-dispersion using a high-speed disperser or sand mill is necessary, and a dispersant should be added to ensure stable suspension of the pigments and fillers.
The application process significantly affects leveling properties. Spraying pressure and distance must be precisely controlled. Too low a pressure will result in insufficient atomization of the paint, forming particles; too high a pressure may cause paint rebound, resulting in a rough paint film. Generally, a spraying pressure of 0.3-0.5 MPa is recommended, with the spray gun 20-30 cm away from the substrate, and a uniform gun speed to avoid excessively thick local coatings. Before spraying, the paint should be thoroughly stirred to prevent pigment sedimentation and uneven color. Simultaneously, ensure the paint temperature is consistent with the ambient temperature to avoid abnormal leveling due to temperature differences. If brushing or roller coating is used, appropriate tools must be selected. Brushes with overly soft bristles or rollers with rough surfaces will leave marks. It is recommended to use rollers with moderate elasticity and smooth surfaces, and control the coating thickness to avoid applying too thick a layer at once.
Environmental factors are an external guarantee for leveling properties. Temperature and humidity significantly affect the drying speed of paint. Excessively high temperatures or low humidity accelerate surface drying, hindering internal leveling and resulting in orange peel texture. Conversely, excessively low temperatures or high humidity slow drying, prolonging leveling time, and even causing sagging. Generally, an ambient temperature of 15-35℃ and humidity not exceeding 80% are recommended for application, which can be regulated using air conditioning, dehumidifiers, etc. Furthermore, the application environment must be kept clean to prevent dust, oil, and other impurities from falling onto the paint film surface, forming particles or pinholes. If applying outdoors, choose windless or lightly windy weather to prevent wind from affecting paint flow.
If the paint film already exhibits poor leveling, it can be repaired through sanding and touch-up coating. For minor orange peel or brush marks, gently sand with fine sandpaper (e.g., 800-1000 grit) until smooth, remove dust, and reapply a topcoat. For severe sagging or particles, thoroughly sand down to the substrate and reapply the primer, intermediate coat, and topcoat, ensuring each layer is fully dried and of uniform thickness. During repairs, it is crucial to ensure consistency between environmental conditions and construction techniques to avoid recurring similar problems.
Improving the leveling properties of water-based steel structure paint requires synergistic optimization of formulation, process, and environment. By selecting suitable leveling agents, adjusting paint viscosity, standardizing application procedures, and controlling environmental parameters, the smoothness and gloss of the paint film can be significantly improved, ensuring that water-based steel structure paint achieves optimal protective and decorative effects.
