Using an orbital sander on walls is an effective way to achieve a smooth, professional finish, especially on drywall or plaster, preparing the surface perfectly for painting or wallpapering.
Preparing for Wall Sanding
Before you begin sanding, proper preparation is key to ensuring safety and achieving optimal results.
Safety First
Your health and safety should be the top priority.
- Eye Protection: Always wear safety glasses or goggles to protect your eyes from dust and debris.
- Dust Mask/Respirator: Fine dust particles from drywall or plaster can be harmful if inhaled. Use a high-quality dust mask or a respirator.
- Gloves: Protect your hands from friction and dust.
- Ventilation: Work in a well-ventilated area. Open windows and doors, or use fans to circulate air. Consider using a shop vacuum with a HEPA filter attached to the sander's dust port for dust collection.
Workspace Setup
Prepare your work area to contain dust and protect your belongings.
- Clear the Area: Remove all furniture, decorations, and items from the room.
- Protect Surfaces: Lay down drop cloths or plastic sheeting on the floor and over any remaining furniture.
- Lighting: Good lighting is crucial to identify imperfections. Use a bright work light positioned to cast shadows, highlighting areas that need more attention.
Choosing the Right Sander and Sandpaper
While various sanders exist, a random orbit sander is excellent for walls due to its ability to create a smooth, swirl-free finish. Its random orbital motion prevents visible sanding patterns.
For sandpaper, selecting the correct grit sequence is vital:
| Grit Type | Purpose | Application |
|---|---|---|
| Coarse (60-80 grit) | Initial smoothing, removing heavy imperfections. | Use cautiously on very rough patches or old paint. |
| Medium (100-120 grit) | General sanding, smoothing out previous coarse marks. | Standard for new drywall or plaster. |
| Fine (150-180 grit) | Final smoothing, preparing for primer/paint. | For achieving a silky-smooth finish before topcoats. |
| Very Fine (220+ grit) | Light scuffing between paint coats. | Not typically needed for initial wall prep, but useful for trim. |
Always progress through grits. Start with a coarser grit to address major imperfections, then switch to a finer grit to remove the scratches left by the previous grit.
Mastering the Orbital Sanding Technique
Proper technique is essential for an even, blemish-free surface.
Getting Started
- Attach Sandpaper: Securely attach the correct grit sandpaper to your orbital sander's pad.
- Power Up: Plug in your sander.
- Initial Grip: Hold the sander firmly with both hands, ensuring a comfortable and controlled grip.
The Sanding Motion
- Start Off-Wall: Turn on the sander before it touches the wall. This prevents the sander from digging into the surface.
- Engage the Wall: Gently bring the running sander to the wall.
- Circular Movements: Make circular movements using the random orbit sander from the inner wall to the outer edges, making sure not to press too hard and as smoothly and evenly as possible.
- Overlap Passes: Overlap each pass by about half the width of the sanding pad to ensure complete coverage and prevent unsanded streaks.
- Maintain Constant Pressure: Let the sander's weight and orbital action do the work. Applying too much pressure can create gouges, slow down the motor, and wear out sandpaper quickly.
- Constant Motion: Keep the sander moving at all times. Dwelling in one spot can create depressions or swirl marks.
- Feather Edges: When sanding near corners or edges, feather your passes to blend the sanded areas seamlessly.
Section by Section
Work in manageable sections, typically 2x2 or 3x3 foot squares. Complete one section before moving to the next, maintaining your overlapping circular motion. This systematic approach helps ensure you don't miss any spots.
Post-Sanding Essentials
Once you've finished sanding, a few final steps will ensure your walls are ready for their next finish.
Cleaning Up
- Vacuum: Use a shop vacuum with a brush attachment to thoroughly remove dust from the walls, baseboards, and floor.
- Damp Cloth: After vacuuming, wipe down the walls with a slightly damp (not wet) microfiber cloth to pick up any remaining fine dust. Allow the wall to dry completely before priming or painting.
Inspection
- Visual Check: Carefully inspect the sanded walls from various angles.
- Light Test: Use a strong work light or flashlight, shining it across the wall at a low angle. This will highlight any remaining imperfections, high spots, or missed areas. Re-sand any problem areas with fine-grit sandpaper.
- Tactile Check: Run your hand over the wall to feel for any rough spots or inconsistencies.
Tips for Best Results
- Don't Skip Grits: Always progress from coarser to finer grits. Skipping grits will leave deeper scratches that will be visible through paint.
- Let the Sander Do the Work: Avoid applying excessive pressure. The sander's own weight and orbital action are sufficient.
- Practice on Scrap Material: If you're new to orbital sanding, practice on a scrap piece of drywall or an inconspicuous area first to get a feel for the tool.
- Regularly Check Sandpaper: Replace sandpaper sheets frequently as they wear out. Dull sandpaper is ineffective and can burnish the surface rather than sand it.
- Proper Storage: Clean your sander after each use and store it in a dry, safe place.
