How To Choose and Use Sandpaper

Sanding is an important step in many home improvement projects, from refinishing furniture to prepping surfaces for paint. The right sandpaper can make the difference between a smooth, professional finish and a subpar result. This guide will help you understand the different types of sandpaper, how to choose the right grit, and the best techniques for sanding various materials. In the video, This Old House general contractor Tom Silva shows the importance of proper sanding techniques and explains how to achieve the best results.

Understanding Sandpaper Grits

Sandpaper comes in various grits, which refer to the coarseness of the abrasive particles on the paper. The lower the grit number, the coarser the sandpaper.

Coarse Grits (40–60)

Coarse grits are ideal for:

• Removing paint or varnish
• Smoothing rough wood surfaces
• Shaping wood quickly

These grits remove material rapidly but leave a rough surface that requires further sanding with finer grits.

Medium Grits (80–120)

Medium grits are suitable for:

• Removing scratches left by coarser grits
• Smoothing bare wood before finishing
• Scuffing surfaces before painting

These grits strike a balance between material removal and surface smoothness.

Fine Grits (150–180)

Fine grits are used for:

• Final smoothing before finishing
• Light sanding between coats of paint or varnish
• Polishing metal surfaces

These grits produce a smooth surface with minimal scratches.

Very Fine Grits (220 and above)

Very fine grits are perfect for:

• Final sanding before applying stain or clear finishes
• Polishing painted surfaces
• Smoothing delicate materials like plastics

These grits create an ultra-smooth surface ideal for high-gloss finishes.

Choosing the Right Sandpaper for Your Project

Selecting the appropriate sandpaper depends on the material you’re working with and the desired outcome. Here are some guidelines.

Wood Sanding

For bare wood, start with a coarse grit (60–80) to remove any rough spots or imperfections. Progress through medium (100–120) and fine grits (150–180) for a smooth finish. For hardwoods, you may need to go up to 220 grit or higher for an ultra-smooth surface.

Metal Sanding

Begin with a medium grit (80–120) to remove rust or old paint. Progress to finer grits (150–220) for a polished finish. For a mirror-like shine, use grits up to 400 or higher.

Drywall Sanding

Use 120–150 grit sandpaper to smooth the joint compound. Be careful not to sand too aggressively, as this can damage the drywall’s paper surface.

Paint Preparation

For surfaces that will be painted, use 120–180 grit sandpaper to create a slightly rough surface that paint can easily adhere to.

Sanding Tips for a Perfect Finish

Effective sanding requires more than just the right grit. Achieving a perfect finish requires attention to detail and proper technique. Follow these tips for best results.

• Excess pressure can create uneven surfaces. Let the sandpaper do the work—use even pressure and long, smooth strokes.
• Worn-out sandpaper can damage the surface. Tap it or use a cleaning stick to keep it clear. Replace it when it loses its effectiveness.
• Always sand in the direction of the wood grain to avoid scratches.
• Clean the surface between grits to remove dust and debris.
• Progress through grits systematically, never skipping more than one grit size.
• Use a sanding block or power sander for flat surfaces to ensure even pressure.

By following these guidelines, you can achieve a professional and smooth finish on any project.

Types of Sanders and Their Uses

Different sanding tasks call for different tools. Here are some common types of sanders:

• Random orbit sander: This versatile tool is suitable for most general sanding tasks. Its circular motion helps prevent visible sanding patterns.
• Belt sander: Ideal for removing large amounts of material quickly, belt sanders are best for rough sanding and flattening surfaces.
• Detail sander: Perfect for reaching tight corners and intricate areas, detail sanders are great for furniture and trim work.
• Hand sanding: For small projects or delicate work, hand sanding with a sanding block or folded sandpaper offers precise control.

Sanding Safety Tips

Sanding can create a lot of dust, which can be harmful if inhaled. Follow these safety precautions:

• Wear a dust mask or respirator to protect your lungs.
• Use safety glasses to shield your eyes from flying particles.
• Work in a well-ventilated area or use dust collection systems.
• Wear hearing protection when using power sanders.

Maintaining Your Sandpaper and Sanders

Proper care of your sanding tools can extend their life and improve their performance:

• Clean sandpaper regularly to prevent clogging.
• Replace worn sandpaper promptly to maintain efficiency.
• Keep power sanders clean and lubricated according to manufacturer instructions.
• Store sandpaper in a dry place to prevent moisture damage.

Common Sanding Mistakes To Avoid

Even experienced DIYers can make sanding errors. Here are some pitfalls to watch out for:

• Skipping grits: This forces finer grits to work harder and can leave visible scratches.
• Over-sanding: Excessive sanding can damage the material or create unevenness.
• Using the wrong grit: Starting with too fine a grit wastes time, while using too coarse a grit can damage the surface.
• Neglecting dust removal: Failing to clean between grits can lead to a poor finish.

Sanding Different Types of Materials

While wood, metal, and drywall are common materials that require sanding, you may encounter other materials in your projects.

Plastics

For plastics, use very fine grits (220 or above) to prevent scratching the surface. Sand gently and evenly to avoid overheating the plastic, which can cause it to warp. For a polished look, consider wet sanding with ultra-fine grits up to 2000.

Fiberglass

Fiberglass requires a cautious approach as it can generate harmful dust particles. Start with medium grit (120) and move to finer grits (240–400) for a smooth finish. Always use protective gear and work in a well-ventilated area.

Painted Surfaces

To refurbish painted surfaces, use a medium grit (120–150) to remove the old paint and smooth the surface. If you’re repainting, a fine grit (180–220) is recommended for the final pass to ensure good paint adhesion.

Sandpaper Types and Their Uses

In addition to different grits, sandpaper is made from various materials suited for specific tasks:

• Aluminum oxide: Versatile and long-lasting, ideal for wood and metal
• Garnet: Best for hand-sanding wood, it wears out faster but provides a finer finish
• Silicon carbide: Suitable for sanding metal, plastic, and fiberglass; can be used wet or dry
• Ceramic: Extremely durable, great for power sanding hardwood and metal

Each type of sandpaper has unique benefits. Selecting the right sandpaper type can enhance your efficiency and the quality of your finish.

Our Conclusion

Choosing and using the right sandpaper is essential for achieving a professional-quality finish on your DIY projects. Understanding grit sizes, selecting the appropriate tools, and following proper techniques can help you sand effectively and efficiently. Remember to prioritize safety and maintain your tools for the best results.

Resources

All the different types of sandpaper and sanders Silva demonstrated can be found at home centers. Silva recommends buying a wide variety of grits to ensure the material gets sanded properly.

Tools