What grit of sandpaper is best for the initial sanding of cured plastic fillers?

For the initial sanding of cured plastic fillers, a coarser grit sandpaper is typically recommended to effectively remove excess filler, shape the material, and create a surface that can be worked on further. Using a grit like 40 allows the user to remove significant amounts of material quickly, enabling a more efficient shaping process.

Coarser grits, such as 40 grit, are designed to tackle tougher materials and can create a more aggressive cut. This helps in preparing the surface for subsequent finer sanding, which smooths the surface and refines the finish. After this stage, finer grits can be introduced to achieve the desired smoothness for paint adhesion or final finish.

The finer grits mentioned, such as 80, 180, or 220, would not be suitable for initial sanding due to their tendency to clog or not effectively shape the filler, which may prolong the sanding process and hinder efficiency in the repair work. Therefore, starting with a coarser grit is crucial for achieving optimal results in the sanding process.