Sanding Drywall: Prepping For Paint
Learn the best techniques for sanding drywall.
Sanding drywall is the final step in the drywalling process. Unlike the muscular work of lifting and installing drywall panels, sanding can be slow work. Make sure you invest in the appropriate equipment and protect yourself and your belongings from dust before you get started. Cleaning up can become a significant part of drywall sanding. You will need to vacuum several times as dust gets into the smallest cracks. Remember that you will be preparing your walls for paint or wallpaper, so make sure you achieve a smooth finish. A good primer or sealer will help hide any imperfections on your walls.
Making sure your walls are smooth is the objective of sanding, but you have to be careful not to oversand. Oversanding joints can damage the paper face of your drywall panels and leave scuff marks or tear marks. Always start out with light sanding and make sure your sandpaper is not too coarse. If you oversand, you may need to fill the scratches in with joint compound.
Preparing for sanding
Sanding drywall creates a lot of dust. Before you begin to sand, you will need to prepare the room and protect yourself from dust inhalation. Even though you will want to completely seal off the room to protect your house from the buildup of a layer of dust, you will also need to properly ventilate the room. Open a window and place a fan in the window to blow the air outside, or use an air cleaner. As you prepare to sand you should keep in mind the following advice:
- Seal off the room with plastic in the doorway so that dust does not escape into the rest of your house.
- Properly ventilate the room, but do not open all windows, as this will cause the dust to circulate.
- Lay a drop cloth on the floor to catch the dust.
- Cover any furniture in the room with plastic.
- Wear goggles and a dust mask to protect yourself from dust inhalation.
- You might also want to wear a hat to keep dust out of your hair.
A mask offers some protection against large particle inhalation. Choose a design that fits tightly. A metallic strip over the bridge of the nose keeps the mask in position and makes it as airtight as possible.
If you are sensitive to dust or just want to try to avoid the dust from sanding, try wet sanding. Use a small-celled polyurethane sponge to wet the walls–the smaller cells help hold the water and prevent it from dripping. However, wet sanding does not create the same fine finish as dry-sanding. Another option for dust-free sanding is using a commercial sanding machine or dust-free tool designed to be attached to a vacuum.
While you may opt for traditional sandpaper to finish your drywall job, there are special sanding tools to help make the work move faster and help minimize dust. Unless you are an experienced drywaller, you will find bumps and ridges along your walls that will take a lot of care to sand smooth. As with all DIY tasks, choosing the right tool for the job is essential. Personal protective equipment, including dust masks, is important to use while sanding drywall, especially if you are sensitive to dust.
Starting to Sand
After you have prepared the room for sanding, take a first pass at the walls with a pole sander with 120-grit sandpaper. Make sure that you use even pressure across the wall and ceiling surfaces. Glide the pole sander across all of the taped seams, blending the joints into the surface of the drywall. You may find it difficult to smooth the inside corners and smaller areas with a pole sander.
The next step involves hand sanding. Before you begin to hand sand, inspect the walls. Pass the palm of your hand over the joints. Use a light to shine on the wall surface you plan to sand, so that it will illuminate the seams, casting light across imperfections and making them evident. Use sandpaper or a hand sander with 150-grit sandpaper. If you use sandpaper, fold it to create an edge.
For details and finishing work, hand sand your walls. Use even pressure in a circular motion to buff out scratches and imperfections (Image 1).
It may take practice to get the same type of finish as hand sanding. Use a sponge to wet the walls and clean the sponge frequently (Image 2).
Pole sanders are used for a first pass at walls and ceilings(Image 3). You can twist the handle to control the ball joint on the sanding head to allow the sander to switch directions and turn around the inside corners.