What is the main advantage of wet sanding gypsum panels with a polyurethane sponge?

• A. It speeds up curing of joint compound.
• B. It increases surface roughness for paint adhesion.
• C. It eliminates dust and prevents scuffing of the drywall surface paper.
• D. It prevents moisture absorption.

Answer: (C)

Wet sanding with a damp polyurethane sponge is used because water acts as a lubricant and carries away fine particles, while the soft sponge minimizes friction against the paper surface. This combination produces a smoother finish and dramatically reduces the amount of drywall dust compared with dry sanding, all while helping prevent scuffing or tearing of the drywall paper. In practical terms, the damp sponge keeps dust down and preserves the integrity of the surface, making touch-ups and priming easier.

It doesn’t speed up curing of joint compound, so that benefit isn’t achieved by sanding. It also doesn’t increase surface roughness—wet sanding aims for a smoother surface, not a rough one. And while moisture is involved in the process, the goal isn’t to prevent moisture absorption in the drywall, but to finish the surface cleanly and with less damage.