How to Wet Sand Drywall

Fill your bucket with water. The temperature should be comfortable to your hand, since you'll be submersing your hand in it repeatedly throughout the sanding process.

Identify the coarse side of your drywall sponge. Just like on a dish-scrubbing sponge (which a drywall sponge resembles), the coarse side will be thinner and rougher. This is the side that will actually be used to sand the wall (the sponge part is just to supply water).

Wet your sponge. Submerge the entire sponge, and then wring most of the water out. You want your sponge to be damp, but not dripping.

Scrub the drywall with the coarse side of the sponge. Use large, circular strokes over big areas, and apply pressure evenly. Pay more attention to spots that extend out or are uneven. Avoid scrubbing too long in one area, however, which can create grooves or dents. It will take a few minutes for the hardened drywall compound to absorb the water and begin to soften, which is necessary for wet sanding.

Monitor the coarse side of your sponge as you scrub. The excess drywall that is rubbed off will collect on the sponge, eventually coating the coarse area and making it too smooth to effectively sand. When this happens, wash the sponge in the water bucket, wring it damp, and start again. Do this repeatedly as you sand.

Watch the water bucket as it collects drywall dust from the sponge. When the water becomes too murky to see through, you will need to empty and refill your bucket. The larger the bucket you use, the less often you will need to do this.