Homeowner’s Guide To Sandpaper
Modern sandpaper doesn't include sand, and it often doesn't include paper, either. It has multiple uses in the shop, on the jobsite or around the house.
Before sandpaper, people used shark skin, rough horsetail and other natural abrasives to smooth and polish. The earliest version of sandpaper, developed in 13th-century China, combined sand with shells and seeds bonded to parchment.
Here in the 21st century, while sandpaper is essential for home improvement and woodworking projects, most of it is not made from sand or paper!
You’ll need sandpaper if you’re smoothing and shaping wood, removing paint or stains or polishing finishes on wood or metal. Sandpaper also comes in handy for many tasks around the house, like cleaning grout, touching up wool and suede and sharpening scissors.
The vast array of sandpaper types available can make choosing the best one(s) for your project difficult and confusing. Here’s what you need to know.
What to Know About Sandpaper
Given the lack of actual sand, it would be more accurate to refer to sandpaper as abrasive paper. It comes in 9-in. x 11-in. sheets, belts, drums, discs and precut pieces for specialty sanding machines.
When you need a “piece” of sandpaper, you’re usually talking about part of a sheet or a whole one. But you could also be referring to a precut piece with hook-and-loop backing for your random orbital or detail sander.
Sandpaper sheets differ in three main ways:
- The abrasive material;
- The size and spacing of the abrasive particles (AKA grit);
- The type of backing, usually a more robust material than paper.
There are also differences in the adhesives that bond the abrasives to the backing, but these generally don’t matter to the user.
Types of Sandpaper and When to Use Them
The different types of sandpaper are best characterized by the abrasive used. There are five types of abrasives:
Perhaps the most common type, aluminum oxide is brittle and crumbles easily, exposing new, sharp edges. It’s good for sanding wood, drywall and painted surfaces. The sheets are gray with thick, cardboard-like paper backing, making it well-suited for orbital sanders. Zirconia alumina, a related material, is great for sanding metal.
A natural abrasive material, garnet gives the product a reddish-brown color. Garnet wears down more quickly than aluminum oxide so a sheet doesn’t last as long, but the softer abrasive produces fewer scratches. This makes garnet paper better for hand-sanding wood and smoothing finishes.
Choose emery for removing corrosion from and polishing metals. The sharp particles scratch too much for use on wood. The backing is a heavy, flexible cloth. This product is usually black, gray or rust, though it can be any color.
Ceramic also imparts a reddish-brown color. Because it’s harder than aluminum oxide, it’s better for rough sanding and heavy-duty sanding machines. It’s also more expensive. The backing is thicker than aluminum oxide and lasts longer. Ceramic paper is often cut into disks for disk sanders, or molded into belts for belt and drum sanders.
This blue or gray sandpaper maintains its abrasive action even when wet. It’s usually mounted on a waterproof backing. It’s the paper you need for wet sanding, polishing between coats of finish and sanding metal or plastic. It’s usually called wet/dry sandpaper.
What Are Grits and Grades?
When shopping for sandpaper, select from various grits, clearly marked on the product packaging.
What does grit mean?
Grit refers to the size of the abrasive particles; it measures coarseness. A coarse piece of sandpaper removes more material at one time than a fine piece, but also leaves deep scratches, which usually require re-sanding with a finer grit. Woodworkers, furniture and floor finishers call this “going through the grits.”
The coarsest grit is 24. You would only use this for a rough sanding job, like removing the finish from a floor or thinning a beam. Finer grits move up the scale to 36, 50, 60, 80, 100, 120, 150, 220, 240, 280, 320, 360, 400 and 600. Grits finer than 600 are used for high-quality polishing.
What are sandpaper grades?
Sandpapers are grouped into grades, with each including a number of grits. The grades are usually listed as:
- Coarse: 24- to 60-grit;
- Medium: 80- to 120-grit;
- Fine: 150- to 180-grit;
- Very fine: 220- to 240-grit;
- Extra fine: 280- to 320-grit;
- Super fine: 360-grit and above.
If you’re looking for utility sandpaper to use around the house, you would generally choose a medium grade. Some manufacturers offer packages containing all the medium grits.
Coarse grades are usually most efficient when used with belt, drum or disk sanders. Fine grades and above are usually reserved for sanding and polishing finishes.