Why is it not advisable to use sandpaper for decal removal?

Using sandpaper for decal removal is typically not advisable primarily because adhesive residue will often remain after the sanding process. When sandpaper is used, it may effectively remove the top layer of the decal, but the adhesive portion often remains embedded in the surface. This leftover adhesive can attract dirt, impair the finish, and potentially affect the adhesion of any new paint or decals applied afterward.

Additionally, while it's relevant to not overlook potential surface scratches or damage to the paint, these concerns are secondary when dealing with the immediate issue of not effectively removing all aspects of the decal. Proper removal techniques usually involve using chemicals designed to break down the adhesive or heat applications, which can wholly eliminate both the decal and its adhesive without risking damage to the underlying surface. Therefore, choosing the right method is crucial to ensure a clean finish free from remnants that could hinder future applications.