During the painting construction phase, water is the "natural enemy" of industrial coatings. High humidity and sudden rainfall can cause a series of problems, from "blushing" (whitening of the paint film) to poor adhesion, and even lead to premature failure of the entire coating. However, project schedules often do not allow us to wait indefinitely for clear weather. PZSSS has compiled a technical solution for you to help meet the challenges of construction in the rainy season.
1. "3-Degree Rule": Dew point is the core key In humid weather, the most important factor is the dew point.
- Core principle: The temperature of the substrate surface must be at least 3°C above the air dew point temperature.
- If the temperature difference is too small, a microscopic water film invisible to the naked eye will form on the metal surface, hindering the strong bonding between the PZSSS primer and the substrate. Before construction, be sure to use a digital thermo-hygrometer to verify this condition.
2. Strictly monitor the upper humidity limit For most high-performance coatings (especially epoxy types), application should not be carried out if the relative humidity (RH) exceeds 85%.
- Exception: Certain special PZSSS moisture-curing polyurethane actually require absorbing a small amount of moisture to harden.
- Warning: For standard coatings, high humidity will trap the solvent inside the paint film, causing the film to become soft and tacky, and it will never achieve the desired cured hardness.
3. Emergency Plan: What to do if rain suddenly occurs during construction?
- Stop work immediately: As soon as it starts to rain, stop spraying immediately and seal all open paint buckets.
- Assess damage: If the paint is wetted by rain before it has dried, "crater"-shaped pits will appear on the surface. After drying, these areas must be sanded and repainted.
- Strictly prohibit "covering" moisture: Never apply paint on a surface that "appears" dry but still feels cold and damp to the touch. Please use an industrial hot air blower to ensure the substrate is completely dry.
