What Is A Sandpaper Grit? How Sandpaper Grit Works
What Is A Sandpaper Grit?
Sandpaper grit is a measure of the size of abrasive particles which are used to smooth surfaces. It is measured on a scale from very coarse to very fine and usually ranges from 24 grit to 2000 grit, with the higher number representing a finer grade and the lower number being for heavier sanding.
Different materials require different grades of sandpaper in order for them to be properly polished or finished.
Coarser grades are better for rougher jobs such as removing rust, while finer grades are better for smoothing wood or metal surfaces.
The roughness or smoothness of sandpaper is determined by its grit size, which is indicated by a gauge number. The lower the number, the coarser the grit, meaning that it has larger abrasive particles. For example, #24 or #40 grit sandpaper is very rough, while #1,000 grit sandpaper is extremely fine.
The grit number is usually printed on the back of the sandpaper. Most commonly used grits range from #24 to #1,000. It is a common misconception that the grit number refers to the number of grit particles per square inch.
The number scale refers to the number of holes per square inch in the screens used during the manufacturing process. Such as 60-grit sandpaper, the abrasive particles used in the paper were sieved through a screen that had 60 holes per square inch.
How Sandpaper Grit Works
Coarser sandpaper with a lower grit number is more aggressive and removes material faster and with less effort than finer sandpaper. It achieves this by cutting the fibers on the surface. This type of sandpaper is ideal for removing large amounts of material, creating a rounded edge, or removing old paint or blemishes. However, it also leaves deep scratches.
On the other hand, very fine sandpaper removes only a small amount of material and is used to smooth surfaces. The higher the grit number, the smoother the surface.
The problem with using too fine of a sandpaper too soon is that it takes longer to achieve the desired result and can burnish the wood surface causing it to appear overworked and hindering the absorption of stains and finishes.
The key is to start with the highest grit that will accomplish the task efficiently and then gradually move to higher grits as the surface nears completion, stopping when it is smooth enough for your desired outcome.
Types of Sandpaper Grit Ranges
Differently graded sandpapers are available, but most sanding projects require the following grit ranges:
#60–#80 Grit: Coarse. This grit is used for cutting through old paint and rough edges, as well as shaping and rounding edges. It should not be used for fine details or sharp edges and corners, and caution should be taken when using it on veneer plywood.
#100–#150 Grit: Medium. This is the most commonly used grit range, and it can be used to work down difficult materials by applying more pressure or to preserve fine materials by applying less pressure. This grit is often used for bare wood surfaces, and a final sanding with 150-grit paper is recommended for wood surfaces that will be painted.
#180–#220 Grit: Fine. This grit range is not typically used on the first run-through, but is used for second or third sandings. It can also be used to roughen glossy paint in preparation for applying another coat, and bare wood that will be stained should not be sanded with higher than 220-grit paper.
#320 Grit: Ultra-Fine. This grit is used to achieve an extra level of smoothness on all types of materials. It is often used to smooth painted surfaces between coats and for wet sanding, which creates a fine, gritty slurry that helps to smooth the surface. It is also used as one of the first grits when sanding down solid surface countertops.
Cost of Sandpaper Grit
Sandpaper is a cost-effective product that comes in a variety of sizes and quantities, including multi-packs with six to 24 or more pieces. These packs can include multi-surface options with different grades or just one grade.
Sandpaper sizes range from large 9″ x 11″ sheets to small 3 1/4″ x 8 3/4″ sheets and even mouse-sized pads. Prices for these packs can range from $2 to over $25.