Sanding before and between painting work: how to achieve a smooth result
A beautiful painting result doesn't start with the paint, but with the preparation. Sanding ensures that old paint layers, small imperfections, and loose parts are removed. Additionally, the new paint will adhere better to the surface.
Even between different paint layers, light sanding can make a big difference. But when is sanding necessary, which grit do you use, and how do you approach it correctly? We'll explain it step by step.
Why do you need to sand before painting?
By sanding a surface, you make it clean, even, and slightly rough. This helps the primer or paint to adhere better.
Sanding is especially important for:
- Removing loose paint
- Smoothing out imperfections
- Matting glossy surfaces
- Finishing filler smoothly
- Improving the adhesion of the next paint layer
- Removing dust and minor flaws between paint layers
If you skip this step, the paint may not adhere as well, or imperfections may remain visible after painting.
Do you always have to sand before painting?
Not every surface needs to be sanded with the same intensity. Nevertheless, light sanding is advisable in many cases.
Already painted walls
If the existing paint layer is matte, clean, and still in good condition, you usually don't need to sand heavily. However, remove loose paint and sand repairs or filled areas smooth.
For smooth or glossy wall paint, it's wise to lightly sand the surface to a matte finish. This allows the new paint layer to adhere better.
New plasterwork or plasterboard
New plasterwork normally doesn't need to be sanded completely. However, check for grains, protrusions, or small imperfections.
For plasterboard, especially the filled joints and screw holes should be sanded smooth. Work carefully so as not to damage the cardboard of the sheets.
Wood
You almost always sand wood before painting. This removes rough fibers and old, loose finishes.
Always sand untreated wood in the direction of the wood grain. For already lacquered wood, first thoroughly dull the existing layer.
Doors, cabinets, and furniture
Smooth surfaces such as doors, kitchen cabinets, and furniture must be thoroughly degreased and sanded. Existing lacquer layers, in particular, can be very smooth.
You don't always have to remove the old paint layer completely. As long as it's firmly attached, it's usually sufficient to sand it evenly and matte.
Metal
For metal, first remove rust, loose paint, and other impurities. Then lightly sand the entire surface. Afterward, apply a suitable primer before further painting.
Which grit sandpaper do you use?
The number on the sandpaper indicates how coarse or fine it is. The lower the number, the coarser the sandpaper.
Coarse grit: P40 to P80
Use a coarser grit for removing:
- Thick or peeling paint layers
- Large imperfections
- Rust
- Rough pieces of wood
Work carefully, as coarse grits can quickly create deep scratches.
Medium grit: P100 to P150
This grit is suitable for:
- Sanding existing paint layers
- Smoothing wood
- Finishing filler
- Preparing for primer or varnish
For many general painting jobs, this is a good starting point.
Fine grit: P180 to P240
Use fine sandpaper for:
- Light sanding between paint layers
- Removing small dust particles
- A smooth finish for lacquered work
- Preparing the final paint layer
Always sand lightly between layers. The intention is not to remove the previous layer again.
Sanding before painting: step-by-step plan
1. Inspect the surface
First, check for loose paint, cracks, pits, or damage. Remove loose parts with a putty knife or paint scraper.
2. Clean and degrease
Do not sand over dirt or grease. Especially doors, cabinets, and furniture must first be thoroughly degreased. Allow the surface to dry completely before you start sanding.
3. Repair damage
Fill holes, cracks, and imperfections with a suitable filler or putty. Allow it to dry sufficiently according to the instructions on the packaging.
4. Sand the surface
Start with a grit appropriate for the condition of the surface. Sand evenly and do not apply too much pressure.
For wood, sand with the grain. On larger flat surfaces, a sanding block or sander can help to work evenly.
5. Remove all sanding dust
After sanding, the surface must be completely dust-free. Use a soft brush, vacuum cleaner, or slightly damp cloth.
Always allow a damp-cleaned surface to dry thoroughly before applying primer or paint.
Do you need to sand between paint layers?
Sanding between paint layers is not always mandatory, but it can significantly improve the final result. Especially for doors, cabinets, furniture, and other lacquered work, this step is highly recommended.
By lightly sanding:
• You remove dust and small irregularities
• You make the surface smoother
• You improve the adhesion of the next layer
• You achieve a smoother and more professional finish
Use fine sandpaper for this, for example P180 to P240. Sand only lightly until the surface feels evenly matte. Then carefully remove all dust again.
Always check the recommended drying and recoating times of the product. A paint layer that is not yet sufficiently dry can be damaged or roll up during sanding.
Sanding between wall paint layers
For regular wall paint, you normally don't need to sand completely after every coat. If you notice small grains, dried paint residue, or visible repairs after the first coat, you can carefully sand those areas smooth.
Then make sure the wall is completely dust-free before applying the next coat.
Sanding between varnish coats
For varnished work, intermediate sanding is more important. Varnish exposes small imperfections more quickly than matte wall paint.
Allow the first coat to dry completely, then lightly sand with a fine grit. Pay extra attention to dust, edges, and any runs. Then remove all sanding dust and apply the next coat.
Sanding by hand or using a sander?
For small areas and hard-to-reach zones, manual sanding is often sufficient. Use a sanding block to distribute the pressure evenly.
A sander is useful for:
• Large doors
• Furniture
• Wooden panels
• Large filled surfaces
• Floors and other extensive projects
Do not apply too much pressure on the machine and keep it moving. Otherwise, grooves or sanding marks may appear. For fine finishes and edges, you usually work more accurately by hand.
Good preparation makes all the difference
Sanding takes some extra time, but ultimately leads to a more beautiful and durable result. Choose the right sandpaper, work calmly, and always make the surface completely dust-free.
Are you unsure about the correct preparation for your painting project? Visit a Paintfactory store. We are happy to help you with advice on the surface, the right sanding material, and the suitable paint.
