1.How to repair minor bumps (only scratches on the coating, no exposed substrate)?
Clean the surface: Wipe the bumps with a dry cloth or alcohol cotton to remove dust and oil (to prevent impurities from affecting the repair effect).
Fill scratches (optional): If the scratches are shallow (depth <5μm), directly use a touch-up paint pen of the same color as the color-coated roll (the color needs to be matched in advance, and you can ask the supplier for special touch-up paint) to evenly apply along the scratches to cover the scratches. ◦ If the scratches are slightly deep, you can first use fine sandpaper (800-1000 mesh) to gently polish the edges of the scratches to make them smooth, and then apply touch-up paint (to prevent the edges from protruding).
Drying and curing: Let it dry naturally for 24 hours (or according to the time specified by the paint pen), and avoid getting it wet or touching it.
2.How to repair moderate bumps (coating peeling off, substrate slightly exposed but no rust)?
Treat the damaged area: Use fine sandpaper to lightly grind the edge of the peeling area to remove coating debris and make the edge smooth (to avoid peeling of the repair paint later). Wipe the exposed substrate with alcohol or rust remover to thoroughly clean the surface (especially the galvanized surface may have oil or oxide layer).
Anti-rust primer: If the substrate is a galvanized sheet, you can directly apply a layer of cold spray zinc paint with a high zinc content to thinly cover the exposed substrate to form an anti-rust barrier. Wait for the primer to dry completely.
Appearance repair: Use a touch-up paint pen or self-spraying touch-up paint of the same color to cover the primer area. The coating thickness is slightly higher than the surrounding area to avoid dents. After drying, use fine sandpaper to lightly grind the surface to make it smoothly transition with the surrounding coating.
3.What are the symptoms of severe collisions?
The substrate is exposed and rusty, or the corners are sunken and deformed. The manifestations are: the corners are obviously sunken, the coating falls off in a large area, the substrate is rusted (reddish brown), and even small pits appear.
4.How to repair serious bumps?
Rust removal and shaping: Use sand (coarse sand 60 mesh → fine sand 320 mesh) to thoroughly polish the rusted area until the smooth substrate (no rust residue) is exposed. If there is a dent, tap it gently to make it flat.
Use a rust remover (such as oxalic acid solution) to wipe the rust-removed area to neutralize the residual rust, then rinse with clean water and dry.
Multi-layer anti-rust treatment: First apply a layer of zinc-based anti-rust paint to cover the entire exposed substrate and the surrounding 2-3cm coating area, and then apply a layer of epoxy primer after drying.
Filling and color repair: If there are small pits at the bump, use putty first, and then use sandpaper to smooth it after drying. Finally, cover it with the same color repair paint, apply it thinly several times, and polish the whole after drying.
5.What are the precautions for repairing?
Color matching: The color of the repair paint must be consistent with the original coating of the color-coated coil (the color number can be customized to the supplier), otherwise there will be obvious color difference, affecting the appearance.
Outdoor scene enhancement: For long-term exposed parts such as outdoor billboards and equipment housings, it is recommended to apply a layer of weather-resistant varnish (such as fluorocarbon varnish) after repair to enhance the UV resistance and water resistance of the repaired area.
Timely treatment: After the bump, it needs to be repaired as soon as possible, especially in humid and coastal areas. The substrate may begin to rust a few hours after exposure. Rust will accelerate the peeling of the coating and increase the difficulty of repair.