1.How to quickly determine the extent of scratches?
Features: Only the galvanized layer is damaged, the steel substrate is not exposed, the zinc layer is exposed at the scratched part but there is no difference in metallic luster, and there is no obvious dent when touched by hand;
Risk: If not treated, white rust may appear first, and red rust may occur after 3-6 months due to the exhaustion of the zinc layer.
Moderate scratches
Characteristics: The galvanized layer is completely scratched, exposing a small amount of steel substrate. Dark gray substrate is visible at the scratched area, and there is no obvious deformation at the edge;
Risk: Red rust spots may appear at the exposed substrate within 24-48 hours, and expand rapidly as the ambient humidity increases.
Severe scratches
Features: Exposed substrate area > 1cm² or depth > 0.1mm, may be accompanied by edge deformation, burrs, or even local depressions (such as caused by mechanical collision);
Risks: Obvious red rust appears in a short period of time (within 12 hours), and water may accumulate in the gaps to form a "closed battery", accelerating local corrosion.
2.What is the emergency treatment plan for minor scratches?
Material preparation
Basic type: cold spray zinc spray or zinc paste with zinc content ≥95%;
Advanced type: zinc-based repair agent with passivation function.
3.How to deal with moderate scratches in an emergency?
Rust remover: neutral rust removal gel (containing corrosion inhibitors to avoid corrosion of the substrate, such as phosphoric acid-based rust remover); Primer: epoxy zinc powder primer (containing zinc powder> 60%, with both cathodic protection and shielding effects) or inorganic zinc-rich primer (high temperature resistant, suitable for industrial environments); Topcoat: acrylic topcoat (outdoor weather resistant) or epoxy topcoat (indoor moisture resistant) compatible with primer.
4.How to deal with severe scratches in an emergency?
Mechanical cleaning tools: wire brush, angle grinder;
Long-lasting primer: two-component epoxy zinc-rich primer (zinc content ≥70%, dry film thickness 50-80μm;
Filling material: if the scratch depth is greater than 0.1mm, epoxy putty should be used to fill the depression;
Topcoat: polyurethane topcoat or chlorinated rubber topcoat.
5.What are the general precautions for emergency response?
Environmental control
The operation needs to be carried out in a dry environment. If it rains or condenses, it needs to be covered with plastic cloth and heated to dehumidify, otherwise the coating will easily bubble and fall off;
When the temperature is below 5℃, it is necessary to use low-temperature curing paint, or heat the substrate to 10-30℃.
Material compatibility
Strong acid rust removers are prohibited on the surface of the galvanized layer, otherwise it will corrode the remaining zinc layer and aggravate the damage;
The primer and topcoat must match.
Subsequent monitoring
The coating status needs to be checked 1 week, 1 month, and 3 months after treatment. If peeling or bubbling occurs, the failed area needs to be immediately removed and re-coated;
Emergency treatment is only a temporary measure. It is recommended to arrange long-term repair within 6 months, especially in highly corrosive environments.