“Running through grits” not only means going from coarse to fine, but also matching the abrasive to the job. Before you stockpile any more sandpaper, make sure what you do buy (and apply) is the right stuff.”
Sanding is one of the most underappreciated steps in woodworking, yet it plays a crucial role in achieving a smooth, polished finish. While few enjoy the process, no one can deny its impact on the final product. Sandpaper does more than just create sawdust—it refines surfaces, removes imperfections, and even sharpens tools. Given the cost of sandpaper over a lifetime, understanding its properties and proper usage can save time, money, and effort. This guide will help you make informed choices for better results.
Understanding Abrasives
Sandpaper functions as a cutting tool, similar to saw blades or router bits. With each pass, its abrasive grains shave off tiny wood fibers, known as swarf. Selecting the right abrasive type ensures efficiency and prevents unnecessary wear on materials and tools.
Types of Abrasives
1. Garnet – A naturally occurring mineral preferred by traditional woodworkers. Its softer grains fracture during use, exposing fresh cutting edges and producing a consistent scratch pattern. However, garnet paper wears quickly and is unsuitable for metalwork or wet sanding.
2. Aluminum Oxide – The most versatile abrasive, used on wood, metal, and finishes. High-quality aluminum oxide paper is friable, meaning it continuously fractures to maintain sharp edges. It is available in various grades, including those with stearate coatings to reduce clogging.
3. Silicone Carbide – Best for fine sanding of metals, plastics, and finishes. Its glass-sharp grains cut quickly but wear out fast under heavy sanding. Most silicone carbide papers are waterproof, allowing for wet-sanding to prevent clogging and improve performance.
4. Synthetics (Alumina Zirconia & Ceramic Aluminum) – The most durable and heat-resistant abrasives, ideal for heavy-duty sanding and metalwork. While expensive, these materials offer superior longevity in power sanding applications.
Choosing the Right Backing
The backing material—cloth, paper, or plastic—affects flexibility, stiffness, and durability. Manufacturers typically match abrasives with the appropriate backing, but understanding these differences helps refine your selection.
- Cloth (X-weight, J-weight) – Highly durable and flexible, best for belt and disc sanders.
- Paper (A, C, D, E, F-weight) – Versatile and available in a range of stiffness levels. C-weight paper is common for random-orbit sanders.
- Film – More expensive but flatter and stiffer than paper, making it ideal for ultra-fine sanding and sharpening applications.
- Specialty products like sanding sponges, pads, and cords allow access to difficult areas without compromising performance.
Advances in Sandpaper Technology
- Micro-Mesh – Uses a cushioned backing to create an ultra-smooth scratch pattern, ideal for polishing and finishing.
- Abranet – A mesh-based abrasive from Mirka that enhances dust extraction, prolonging sandpaper life and improving shop cleanliness. Best used with multi-holed sanding pads for optimal performance.
Understanding Grit Ratings
Grit numbers indicate particle size, but grading systems vary. Historically, the U.S. used the CAMI scale, while Europe used FEPA (identified by a “P” prefix). Most manufacturers now use FEPA, but older stock may still follow CAMI ratings, causing discrepancies. For fine sanding, knowing these differences helps ensure a consistent finish.
- 220-grit (CAMI) = 240-grit (FEPA)
- 400-grit (CAMI) = 600-grit (FEPA)
Smart Sanding Practices
Sanding should be efficient, not excessive. The goal is to remove surface imperfections without over-sanding.
- For film finishes (varnish, lacquer) – 150–180 grit is sufficient.
- For oil finishes – 220 grit is usually adequate.
- For blotch-prone woods (cherry, pine) – Finer grits (320–400) can help minimize uneven absorption.
Extending Sandpaper Life
Abrasive cleaning sticks can remove built-up debris, restoring sanding efficiency. Additionally, products like the Sander Sitter from Baxter Creek Tools provide a resting spot for random orbit sanders while cleaning discs automatically.
Conclusion
Selecting the right sandpaper and using it effectively can significantly improve your woodworking results. Understanding abrasive types, backing materials, and grit ratings allows for better decision-making, saving both time and materials. By sanding smarter—not harder—you’ll achieve professional-quality finishes with less effort.
