What role does sanding or compounding play in creating a mechanical bond?

Sanding or compounding plays a crucial role in creating a mechanical bond by increasing the surface area for better adhesion. When surfaces are sanded or compounded, their texture is altered, creating microscopic grooves and imperfections. This roughened surface allows the adhesive properties of paints, primers, or other coatings to interlock more effectively with the substrate, resulting in a stronger bond.

A smoother surface, one that lacks these imperfections, would have limited contact points for the coating to adhere, potentially leading to peeling or flaking over time. By increasing the surface area, sanding or compounding ensures that the adhesives have more opportunities to form strong connections, thus improving the durability and longevity of the repaint or refinishing job.

The other choices mention various aspects of finishing but do not directly relate to the formation of a mechanical bond. Decreasing gloss, removing defects, or enhancing vibrancy are important for the aesthetic quality of the finished product but do not address the fundamental interaction between surfaces that allows for the mechanical bond to be established.