Sanding is useful for many projects that use a wide variety of materials, including drywall, metal, and wood. Sanding can be done with power sanders or by hand, and the former tends to deliver the best finishes. Sanding by hand can work well for finishes that require a lighter touch, and power sanders are a better option in the earlier stages. But both sanding approaches use sandpaper, and there are various sandpaper grit options to choose from.
For many people, this compels them to ask the question, “how does sandpaper grit work?” and answering that question will be the focus of this article.
What Does Sandpaper Grit Mean?
When we talk about sandpaper grit, we’re referring to the size of the abrasive materials on the surface. The is expressed as a rating; the higher grit numbers are finer abrasive surfaces that make the finish smoother.
The lower sandpaper grits are coarser abrasives, and they remove large amounts of material quickly. The grit is measured with REPA (Federated of European Producers of Abrasives) and CAMI (Coated Abrasives Manufacturing Institute) standards. The FEPA standards are marked with a “P” designator, and they are divided into two broad groups, micro, and macro. Within those groups, there are many sandpaper grades and grits to choose from. Let’s take a look at these choices in more detail:
● Micro Grit Sandpaper: These are finer abrasives with high grit numbers, and they are typically used for wood finishing and drywall sanding.
● Macro Grit Sandpaper: These are medium to coarse sandpaper grits and grades that are typically used for tough wood and metal surfaces that require a strong approach.
Selecting Grit Sandpaper Materials
The type of abrasive material and the density of the grit will determine the sanding performance for your next project. Certain grit grain types are well suited to smooth sanding, and manufacturers usually list the ideal sanding materials on the product labels.
So, it’s a good idea to know the type of sandpaper grit that you need before you make a final choice. Let’s examine six sandpaper grit options and how they could be used:
- Aluminum Oxide: This a synthetic grit; it’s very durable and a great sanding option for sanding and polishing alloy steel, bronze, and hardwoods.
- Emery: This is a natural grain; it’s commonly used to polish metals and for the removal of corrosion. This is not a good option for sanding wood because the grit particle edges are too sharp.
- Flint: Another natural and durable grain choice, it’s ideal for sanding old surface coatings, such as paint and varnish.
- Garnet: This is a natural grain that’s softer than emery or flint, and garnet sandpaper tends to dull quickly on metal. This grain is a great option when you want to fine sand and finish wood.
- Silicon Carbide: This is the most durable synthetic abrasive on the market at this time. It can be used to sand a wide range of materials, including hardwoods, metal, plastics, softwoods, and more.
- Zirconia Alumina: This is a long-lasting synthetic sanding material that is commonly used for initial sanding on rough wood and removing metal burrs. When this material is used to sand metal, the grit particles become sharper, and this reduces the frequency of sandpaper changes.
What Are Sandpaper Grades?
Now that you have an answer, how does sandpaper grit work? It’s time to expand on that knowledge with a discussion about sandpaper grades. This is a broad term; each grade is a representation of a range of grits.
As an example: A medium grade sandpaper could have grit sizes in the 80-150 range. Let’s take a brief look at the five sandpaper grades to illustrate this further:
- Extra Coarse Sandpaper: This is a 24-36 grit material that is typically used for floor sanding because it has a rapid removal rate for rough surfaces.
- Coarse Sandpaper: This is commonly used for the removal of paint or varnishes or the rough shaping of wood.
- Medium Sandpaper: This is used to remove planing marks and for final shaping work.
- Fine Sandpaper: This sandpaper grade is used for final sanding before the work-piece is finished, and further sanding may be necessary for a smooth finish.
- Extra Fine Sandpaper: This grade is used to achieve an exceptional finish between coats of paint or varnish.
Most projects would begin at one of the lower sandpaper grades and then move up to finer sandpaper for successively smoother finishes.
In the following table, we have an explanation of each sandpaper grit and the typical applications in more detail:
|Grit Number Range
|The Jobs It’s Used For
|40-60 (CAMI)P40-P50 (FEPA)
|Removing a layer of debris
|80 (CAMIP60-P80 (FEPA)
|Sanding bare wood
|100-120 (CAMI)P100 or P120 (FEPA)
|Cleaning plaster, removing watermarks on wood, and final preparation for finishing
|800-1000 (CAMI)P1500, P2000 or P2500 (FEPA)
|Final sanding and polishing
How Do You Know What Grit Sandpaper To Use?
The sandpaper grit size that you choose should match the sanding job that you’re tackling. Heavy sanding and stripping tasks require coarse sandpaper with 40-60 grit. If you’re smoothing and removing minor imperfections at medium grade sandpaper with 80-120 grit will get the job done. If you need a smooth finish, an extra fine sandpaper with 360-600 grit is a good choice.
What Grit Should I Use First?
Complex sanding jobs will necessitate you move through the grist from a lower-grade grit to increasingly finer grits to make the surface smooth. As you move up to the next grit, you will be removing the sanding scratches from the previous sanding stage.
What Grit Is Very Fine?
The ultra-smooth surfaces that you want are achieved with a very-fine 150, 180, and 220 grit. These are typically used to sand paint, polyurethane varnishes, lacquer, and other old coatings before a fresh coat is applied. Moving up to an extra fine, 320 or 360 grit is usually reserved for sanding finishes before polishing occurs.
What Sandpaper Gives A Smooth Finish?
Extra or ultra-fine sandpaper grit is used to add an extra smooth layer to various materials. When this is applied to wood, it’s usually used to smooth the dried layers of paint before the next coat is added.
What Is 2000 Grit Sandpaper Used For?
This is used for polishing light paint textures and scratches in a clear coat.
What Is 2500 Grit Sandpaper Used For?
This sandpaper is soaked in water for wet sanding applications to remove minor scratches from automobile surfaces.
We hope that we’ve answered the question, how does sandpaper grit work? Sandpaper is versatile; you can use it with your hands or attach it to a power sander as needed. As the grit dulls, it’s important to change the sandpaper, or you make the task much harder.
Take some time to choose the correct sandpaper grit for the sanding task, and the results will be more impressive.
I’m Thomas Steven with more than 12 years of experience in woodworking. It has always been my passion to become a successful woodworker. I have completed hundreds of successful projects. This blog is a way of sharing my woodworking experiences and what tools get the best results. I write about woodworking while being an associate with Amazon and I earn a little commission from every qualifying purchase.