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Wet Sanding

Wet sanding is a sanding process that uses water or another liquid as lubrication to wash away grit particles. Without the liquid, the sandpaper can build up with material, causing scratches that ruin the finish. In general, the best liquid to use for most materials is water with a little bit of detergent in it.

Why Wet Sand?

The purpose of wet sanding is to get an even surface finish after dry sanding. Dry sanding shapes the surface, while wet sanding removes the large scratches left by dry sanding. If done correctly, the surface will gradually level out, and the scratches will become smaller and smaller until they are no longer visible when the light reflects off of them.

It is important to use sandpaper that is specifically rated for wet sanding. The sandpaper can be folded over on itself to make a thicker piece, but it is even more effective if wrapped around a backing pad. Another option is to use sanding sponges with the abrasive already attached. By doing so, the sanding surface is able to conform to the shape of the material more easily.

To thoroughly wet sandpaper, many people suggest soaking it overnight in liquid. By doing so, the paper will not absorb any more moisture during the sanding procedure. If you can't soak the paper overnight, aim for at least 15 minutes of immersion before sanding.

It should also be noted that the physical process of wet sanding is different from dry sanding. For an even finish, dry sanding uses small circles, while wet sanding uses linear movements and alternate directions between passes. This is done to remove scratches from previous passes. Wet sanding only removes surface scratches and not much material, so use a light touch.

Benefits of Wet Sanding

  • Better Dust Reduction with Wood

  • Supports Paint Correction for Automotive

When Should You Wet Sand?

It’s best to wet sand when you’re looking for a super smooth finish, or when sanding is going to create a huge mess, and you’re willing to spend a long time sanding to avoid that. If you have a lot of material to remove, then dry sanding is probably a better choice.

From a woodworking perspective (my specialty) it really makes the most sense to wet sand at the end of a project, after you’ve already applied the finish and want to smooth out any brushstrokes or dust nibs.

It doesn’t make sense to wet sand bare wood, for a couple of reasons. First off, you don’t want a super smooth finish yet; fine sawdust clogs wood pores, and makes wood more difficult to stain.

Secondly, wood is sanded in order to remove manufacturing marks or flaws in the wood. To do this, you’re going to need to take off a fair amount of wood. It would take forever to do that while wet sanding. But wet sanding is great for smoothing out the final coat of wood finish.

How to Wet Sand Drywall to Avoid Dust

MATERIALS:

  • Drywall Sponge or Sandpaper Meant for Wet Sanding (Here Is the One I Used)

  • Bucket

  • Water

  • Scrubber (Optional but Does Help)

STEP 1: WET THE SANDING SPONGE

Fill the bucket with warm water, about half to three-quarters of the way full. Dip the sanding tool into the water and wring out the excess.

STEP 2: SAND THE BUMP SPOTS

Start off by focusing on the bumpiest areas for your first pass. Move the sanding sponge against the drywall in a circular motion over the high spots. Don’t press too hard when sanding in one spot because this can create a crater, valley, or holes in the area. Resist the temptation of scrubbing aggressively to speed up the process because, in the end, it will cause you more work.

STEP 3: SMOOTHING IT OUT

Once the bumps are gone, focus on smoothing out the edges. This reduces the visibility of the seams after painting.

STEP 4: ALLOW THE WALL TO DRY

Once the area is completely smooth, let it dry overnight before applying another coat of compound or paint.

Does Wet Sanding Remove Clear Coat?

Keep in mind that compounding or wet sanding does remove clear coat. Many detailers feel you have some wiggle room with the UV layers in the clear coat; however, one-third of the thickness of a Ziploc sandwich bag isn't much at all, and one color correction is not the end of it.

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