When is it necessary to use a sanding block during paint preparation?

Using a sanding block during paint preparation is essential for ensuring even pressure and achieving a smooth finish over large flat surfaces. The primary advantage of a sanding block is that it helps maintain a flat surface imperfection while sanding. This technique prevents uneven wear and prevents creating hollows and highs that can affect the final paint application.

When sanding by hand, without a block, it can be challenging to apply uniform pressure consistently, leading to uneven spots that may result in an undesirable surface texture. Additionally, a sanding block allows the technician to control the sanding process better, making it easier to achieve the desired smoothness, which is critical for the subsequent paint layer to adhere correctly and appear uniform.

Other methods such as creating patterns or removing old paint may not necessitate the use of a sanding block, and while enhancing paint adhesion is important, it's not the primary function of a sanding block in this context.