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The core of aging repair for color steel coils is targeted treatment according to the degree of damage, with priority given to stopping losses (preventing corrosion diffusion), and then restoring protective performance. The specific methods are as follows:

1. Mild aging (only coating fading, powdering, no damage or rust)

Thoroughly clean the surface first: use a neutral cleaner and a soft brush to remove dust and oil stains, rinse with a high-pressure water gun, and air dry to avoid impurities affecting the repair adhesion;

• Grinding and roughening: Use fine sandpaper to lightly grind the surface of the coating to enhance the adhesion of the new coating;

• Touch up protection: Spray the same type of color steel special paint (such as PVDF, HDP topcoat) as the original coating, and apply multiple thin coats to ensure uniform coverage and restore UV resistance and corrosion resistance.

2. Moderate aging (coating damage, localized substrate rusting)

Rust removal treatment: Use an angle grinder combined with a wire brush to polish the corroded area until the clean substrate is exposed, and polish the edges to a smooth transition surface to avoid sharp edges that may cause cracking of the new coating;

Anti rust primer: Apply epoxy zinc rich primer, use the zinc layer to sacrifice the anode to protect the substrate, and wait for the primer to completely dry (according to product instructions);

Surface repair: Apply intermediate paint and topcoat in sequence, seamlessly connecting with the surrounding intact coating to ensure no obvious color difference or interface.

3. Severe aging (severe corrosion of substrate, appearance of holes/deformation)

• Partial replacement: Cut and remove severely damaged areas, cut and remove color steel coil segments of the same specifications and materials, polish the edges, fix them with self tapping screws or rivets, and seal the joints with weather resistant sealant;

Overall renovation: If the aging area exceeds 30% and the local repair effect is limited, it is recommended to dismantle the old color steel coil as a whole and replace it with a new high-quality color steel coil to fundamentally solve the aging problem.

Key precautions

Before repairing, it is necessary to ensure that the construction environment is dry and ventilated, and avoid operating in rainy or high humidity weather;

All coatings must match the original coating type to avoid compatibility issues that may cause detachment;

Regularly review after repair, especially for aging prone areas such as seams and corners, and promptly supplement protection.