Why is using the correct grit sandpaper important?

Using the correct grit sandpaper is essential for maintaining the integrity of the surface being worked on. Different grits have specific applications; for instance, coarse grits are used for heavy material removal or shaping, while finer grits are ideal for smoothing surfaces or preparing them for painting. If you use a grit that is too coarse, you risk damaging the surface, which can lead to imperfections that become visible after painting. Conversely, using a grit that is too fine may not effectively remove the previous layer of paint or prepare the surface adequately for adhesion, resulting in a poor bond between layers. Therefore, selecting the appropriate grit ensures that the sanded area achieves the desired smoothness and prepares the surface optimally for further treatment without causing harm.