I. Common problems during application
1. Sagging (Paint Running): Paint runs downwards after being applied to a vertical surface, forming an uneven paint film.
Main causes: Spraying too thickly, spraying too close (<15cm), low ambient temperature leading to slow drying, paint that is too thin.
Solutions: Use a "thin spray, multiple layers" method, with 3-10 minutes between each layer; maintain a distance of 20-30cm between the spray nozzle and the surface; control the ambient temperature at 15-25℃ and humidity at 40%-70%.
2. Orange Peel Effect (Uneven Paint Surface): After the paint film dries, the surface has a grainy texture similar to orange peel.
Causes: Improper spraying pressure, uneven paint atomization, high ambient temperature leading to rapid surface drying.
Solutions: Adjust the spraying air pressure to ensure sufficient paint atomization; avoid application in high-temperature or strong-wind environments.
3. Undercoat Bleeding (Topcoat Softens Undercoat): Topcoat solvents penetrate the substrate, causing the primer to wrinkle or peel.
Causes: Applying the next coat before the primer is fully dry, or incompatible primer and topcoat.
Prevention: Ensure the primer is completely dry before applying the next coat; choose a compatible paint system.
4. Particle Formation (Rough Paint Film Surface): Fine particles appear after the paint film dries.
Causes: Dusty working environment, clogged spray nozzles, unfiltered or deteriorated paint.
Remedies: Clean the environment and tools before application; filter the paint before spraying; regularly clean the spray nozzle with thinner.
5. Poor Adhesion (Paint Film Peeling): The paint layer does not bond firmly to the substrate, easily causing blistering and peeling.
Key Factors: Inadequate surface preparation (e.g., no sanding, oil stains), steel not meeting Sa2.5 rust removal standards, poor coating compatibility.
Improvement Measures: Thoroughly clean and sand the substrate to ensure a roughness Rz of 30–80μm; use a specialized sealant to enhance interlayer adhesion.
II. Common Problems During Storage and Use
1. Skinning (Forming a Hardened Paint Skin): If the paint is not properly sealed after opening, the liquid surface oxidizes upon contact with air, forming a hard skin.
Causes: Unsealed container, excessively high storage temperature, excessive drier.
Solutions: Immediately tighten the cap after use; for short-term storage, pour the paint into a small bottle and store it upside down to reduce air contact.
2. Sedimentation and Clumping (Pigment Settling): After prolonged standing, the pigment settles, and in severe cases, it forms hard lumps that are difficult to stir evenly.
Causes: Excessive storage time, excessively high temperature (>28℃), excessive thinner, or insufficient grinding.
Treatment: Shake or turn the paint container regularly; for slight sedimentation, stir thoroughly with a wooden stick; hard lumps must be filtered before use.
3. Layering (Separation of Liquid from Water-Based Paint): Water-based paints exhibit a clear upper layer and a thick lower layer after storage.
Causes: Improper thickener selection, pH imbalance, or excessively low storage temperature leading to demulsification.
Solutions: Adjust the proportion of HEUR/HASE type thickeners in the formula; avoid low-temperature storage and maintain a stable environment.
4. Thickening or Gelming: The paint viscosity increases abnormally, even to the point of being unusable.
Inducing Factors: Water ingress into the container, excessively high acid value reacting with the pigment, or large fluctuations in storage temperature.
Remedies: Add an appropriate amount of matching thinner to adjust the viscosity, but discontinue use if severely deteriorated.
5. Difficulty Opening: The seal is too tight or there is negative pressure, making it difficult to open.
Tips: Wrap the lid with a cloth to increase friction and gently tap the edge of the lid to loosen the seal; use a flathead screwdriver to pry evenly along the seam, taking care to protect the rubber gasket.
