How can shallow scratches in sheet metal be repaired effectively?

Burnishing is an effective method for repairing shallow scratches in sheet metal because it involves the process of rubbing or polishing the surface, which not only smooths out the scratch but also works the material back to its original state without removing any additional metal. This method helps in minimizing the visual impact of the scratch while maintaining the integrity and strength of the material.

In contrast, while sanding can remove the scratch, it can also create a rougher surface texture and potentially weaken the area by removing too much material. Applying paint may camouflage the scratch but does not actually repair the physical damage. Using filler material is usually more appropriate for deeper scratches or dents, where additional material is required to restore the surface profile, rather than simply smoothing out the defect. Therefore, burnishing is the most suitable technique for this specific scenario.