When it comes to sanding wood or any other material, choosing the right sandpaper grit is crucial. Sandpaper grit refers to the coarseness or fineness of the abrasive particles on the sandpaper surface. The grit number indicates the size of the particles, with lower numbers representing coarser grits and higher numbers indicating finer grits. In this guide, we will demystify sandpaper grits and help you understand which grit sandpaper to use for different applications.
Sandpaper Grit Numbers Explained
Sandpaper is made up of fine particles, known as grains or grit, which are bonded to a backing material such as paper, sponge, or cloth. The grit particles are sorted by size and adhered to the backing material using adhesive. In the United States, grit sizes are determined based on a scale established by the Coated Abrasive Manufacturers Institute (CAMI). The higher the grit number, the finer the sandpaper grit.
It’s important to note that different countries may use different grit sizing systems. For example, the Federation of European Producers of Abrasives (FEPA) uses a different scale, indicated by the letter “P” preceding the grit number. While FEPA sizes are not identical to CAMI sizes, you can find similar options by selecting the two closest FEPA numbers.
To make it easier for you to choose the right sandpaper grit, we have compiled a sandpaper grit chart:
| Grade | CAMI Grit Range | FEPA Grit Range | Description | Common Uses |
|---|---|---|---|---|
| Extra Coarse | 24-36 | P12-P30 | Sanding extra rough and uneven surfaces | Removing stubborn paint and varnish |
| Coarse | 40-50 | P40-P50 | Sanding rough and uneven surfaces | Rough shaping of wood, removing old finishes |
| Medium | 60-80 | P60-P80 | Smoothing wood surfaces prior to painting | Sanding rough wood, removing scratches and planning marks |
| Fine | 100-120 | P100-P120 | Light sanding between finishes, removing scratches | Light sanding between drywall coats, removing scratches |
| Very Fine | 150-220 | P150-P220 | Sanding bare wood, light sanding between coats, removing scratches from lower coarse grits | Sanding bare wood, light sanding between drywall coats, removing scratches from lower coarse grits |
How to Choose the Right Sandpaper Grit
Choosing the right sandpaper grit depends on the task at hand. Manufacturers may indicate the grit either by number or by describing it, so it’s helpful to know what each description means. Here’s a breakdown of the different sandpaper grits and their common uses:
- Extra Coarse (24-36 grit): This grit is used for removing paint and varnish from rough and uneven surfaces. It’s ideal for sanding tasks that require heavy material removal, such as refinishing old floors.
- Coarse (40-50 grit): Coarse sandpaper is suitable for rough shaping of wood and removing old finishes like light coats of polyurethane. It helps prepare the surface for further sanding or finishing.
- Medium (60-80 grit): Medium grit sandpaper is used for smoothing wood surfaces prior to painting or applying finishes. It’s also effective in sanding rough wood and removing scratches and planning marks.
- Fine (100-120 grit): Fine grit sandpaper is commonly used for light sanding between finishes. It can remove scratches created by coarser grits and provides a smooth surface for the final finish.
- Very Fine (150-220 grit): Very fine grit sandpaper is ideal for sanding bare wood and achieving a smooth surface. It’s also useful for light sanding between coats of paint or varnish and can remove scratches left by lower coarse grits.
On most projects, you’ll start with a coarser sandpaper grit and gradually switch to finer grits to achieve a smooth and polished finish. It’s essential to test the sandpaper on an inconspicuous spot or scrap material before using it on your project to ensure it achieves the desired result.
Types of Sandpaper Grit Material
In addition to different grit sizes, sandpaper is also available in various materials. Knowing the type of grit material that suits your sanding needs is important. Here are the most common types of sandpaper materials:
- Flint: Flint sandpaper features pulverized flint or quartz particles on its surface. It’s the oldest type of sandpaper and is known for being inexpensive. Flint sandpaper is suitable for light sanding and polishing tasks, such as removing varnish and paint.
- Emery: Emery sandpaper is made of a natural grain that’s often used for removing corrosion and polishing steel and other metals. It’s not recommended for sanding wood due to the sharpness of its particles. Emery cloth, which has the abrasive glued to a cloth backing, is more durable than traditional sandpaper and is ideal for deburring or paint removal.
- Garnet: Garnet is a natural grain material that is slightly softer than flint and emery. It’s commonly used for polishing and fine sanding of wood, leather, and plastic. Garnet sandpaper tends to wear quickly but provides a finer finish on the surface.
- Zirconia Alumina: Zirconia alumina is a synthetic abrasive grain that was the most abrasive grain available before ceramic. It’s long-lasting and ideal for grinding away burrs on metal and for initial sanding of rough wood. Unlike other sandpaper materials, zirconia alumina particles can become sharper when sanding metal, reducing the need for frequent sandpaper changes.
- Aluminum Oxide: Aluminum oxide is a durable synthetic grit material that’s well-suited for sanding and polishing various types of metal, including bronze and alloy steel. It’s also suitable for sanding all types of hardwoods and is available in a range of grits from fine to coarse.
- Silicon Carbide: Silicon carbide sandpaper is often used for automotive projects or wet sanding tasks like polishing marble or stone. It’s available in coarse grits for rust removal and fine grits for polishing. Silicon carbide is highly versatile and can be used for sanding plastic, metal, hardwoods, and softwoods.
Conclusion
Choosing the right sandpaper grit is crucial for achieving the desired results in your sanding projects. By understanding the different sandpaper grits and their common uses, you can select the appropriate grit size for your specific task. Additionally, knowing the various sandpaper materials allows you to choose the most suitable option for the material you are sanding. Whether you’re working on wood, metal, or other surfaces, selecting the right sandpaper grit and type will help you achieve a smooth and polished finish. Remember to test the sandpaper on a small area before using it on your project to ensure optimal results. Happy sanding!
