As a home improvement and painting expert with years of experience in various painting projects, I can provide you with a comprehensive answer to your question about the necessity of sanding after painting.
When it comes to painting, the process is not just about applying a coat of paint and calling it a day. It involves several steps to ensure that the final result is not only visually appealing but also durable and long-lasting. One of these steps is sanding, which plays a crucial role in the overall quality of the paint job.
Sanding is the process of smoothing a surface to prepare it for the next coat of paint or to remove the old paint. It is an important step that can affect the texture and finish of the paint job. Here's why:

1. Smooth Surface: Sanding helps to create a smooth surface by removing any imperfections, such as bumps, ridges, or rough spots. This is particularly important if you are painting over an old, chipped, or peeling paint. Without sanding, these imperfections can show through the new paint, resulting in a less than perfect finish.

2. Improved Adhesion: Sanding can also improve the adhesion of the new paint to the surface. By creating a slightly rough texture, it allows the paint to bond more effectively, which can help to prevent peeling and chipping in the future.

3. Texture Control: As you mentioned, if you don't sand between coats, the finish may have a grainy texture. Sanding between coats can help to achieve a smoother finish. This is especially important for areas like trim, where a smooth finish is desired.

4. Removal of Old Paint: Sanding can also be used to remove old paint that is loose or peeling. This can help to ensure that the new paint has a clean surface to adhere to, which can improve the longevity of the paint job.

5. Preparation for Top Coats: Sanding is also necessary before applying top coats, such as varnish or sealant. These coats are designed to protect the paint and add a final sheen or gloss. However, they will only be effective if the underlying paint is smooth and well-prepared.
When sanding, it's important to use the right type of sandpaper or sanding sponge. For trim and other areas where a fine finish is desired, a fine-grit sanding sponge is recommended. This will help to achieve a smooth finish without damaging the wood or other materials.
After each sanding, it's crucial to clean the surface thoroughly. This can be done by vacuuming the trim to remove any large particles, followed by wiping it down with a tack cloth to get rid of any remaining dust. This ensures that the next coat of paint or top coat will adhere properly and won't be marred by dust or debris.
In conclusion, while it may seem like an extra step, sanding is a necessary part of the painting process that can significantly improve the quality and longevity of your paint job. By taking the time to sand between coats and properly prepare the surface, you can achieve a smooth, professional-looking finish that will stand the test of time.
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And if you don't sand the surface smooth between coats, the finish may have a grainy texture. For a smooth finish, sand the trim before applying each coat of paint.Sand the trim with a fine-grit sanding sponge. ... After each sanding, vacuum the trim, then wipe it down with a tack cloth to remove the dust.read more >>