As a woodworking expert with years of experience, I can provide you with a comprehensive guide on what grit to use when sanding wood before painting.

Wood sanding is a crucial step in preparing the surface for a smooth and professional-looking paint job. The choice of grit depends on the condition of the wood surface and the desired finish. Here's a detailed breakdown:

Coarse Grit Sandpaper (Under #100)
Coarse grit sandpaper is typically used for heavy-duty sanding tasks. It is designed to remove large amounts of material quickly, which makes it suitable for rough or unfinished surfaces. However, it can leave deep scratches and is not recommended for fine wood finishes. Using a coarse grit on fine wood can damage the natural grain and result in a rough surface that will be difficult to achieve a smooth paint finish on.

Medium Grit Sandpaper (#120 and #150)
Medium grit sandpaper strikes a balance between coarse and fine grits. It is ideal for removing old finishes, scratches, and minor imperfections without causing significant damage to the wood. Sanding with medium grit will leave a relatively smooth surface, but it may still require further sanding with a finer grit to achieve a perfectly smooth finish.

Fine Grit Sandpaper (#220)
Fine grit sandpaper, such as #220, is often used for the final light sanding just before applying a stain or paint. It is designed to remove minor scratches and create a very smooth surface. Fine grit sandpaper will not remove as much material as coarser grits, but it will refine the surface to a high degree, preparing it for a seamless paint application.

Steps for Sanding Wood Before Painting:


1. Assess the Wood Surface: Begin by examining the wood surface to determine its condition. Look for any rough spots, old finishes, or scratches that need to be addressed.


2. Start with Medium Grit: If the wood has an old finish or visible scratches, start with a medium grit sandpaper like #120 or #150 to remove these imperfections.


3. Progress to Fine Grit: After the initial sanding with medium grit, switch to a fine grit sandpaper like #220 for a final light sanding. This will ensure that the wood surface is smooth and ready for painting.


4. Clean the Surface: After sanding, it's important to clean the wood surface to remove any dust or debris. Use a tack cloth or a vacuum with a brush attachment to ensure the surface is clean.


5. Inspect and Repeat if Necessary: Inspect the surface for any remaining imperfections. If needed, repeat the sanding process with the appropriate grit until the desired smoothness is achieved.


6. Prime and Paint: Once the wood is sanded and cleaned, apply a primer if necessary, and then proceed with painting.

Key Points to Remember:
- **Do not use coarse grits on fine wood finishes.**
- **Medium grits are suitable for removing old finishes or scratches.**
- **Fine grits are ideal for the final sanding before painting.**
- **Always clean the surface after sanding to prepare it for painting.**

By following these steps and choosing the right grit sandpaper, you can ensure a smooth and professional-looking paint job on your wood surfaces.

read more >>

180 to 220 Grit Sandpaper: Finer grit sandpaper is great for removing the scratches left by coarser grits on unfinished wood and for lightly sanding between coats of paint. 320 to 400 Grit Sandpaper: Very fine grit sandpaper is used for light sanding between coats of finish and to sand metal and other hard surfaces.read more >>