All Sandpaper Is NOT Created Equal!

Have you always thought sandpaper was just sandpaper? Or maybe wondered if sandpaper came in different varieties? I used to think this way about every tool out there! But there is always an opportunity for comparing and learning. Ultimately, you want your buying power to reflect how much you are willing to spend and what you are ultimately going to do with your purchase.

There are many categories to my tool belt and toolbox. I always have my “go-to” things in stock and plenty of it. Sandpaper is always one of those things. I never hesitate to buy more, because I know I will always have a use for it and won’t allow it to go to waste. It’s important to know what each type of sandpaper to use and when.

I will start by saying “All sandpapers are not made equally” or rather “All sandpapers will not perform equally.” By sharing my experience, my goal is to empower you with knowledge and to inspire you to flex your creative muscle. The way I see it, by sharing my pitfalls and successes (‘cause I’ve had many), I will hopefully prevent you from experiencing common roadblocks that will hinder you from an enjoyable “do-it-yourself” experience.

Marry The Paper! Say What?

The next time you pull a piece of sandpaper out of a drawer, take a good look at it. Does it have a paper, Velcro or mesh backing? Is it circular or square? What color is the abrasive side? Does it have numbers and letters printed on it? The answers to all of these questions follow a code of colors, letters and numbers, making it easier to determine the abrasive you have and what it is for. Better yet, the next time you are walking down the sandpaper and abrasives aisle of your local hardware, paint, or home & garden store, stop and look at all the options. You will see different sandpaper for wet/dry sanding, furniture finishes, drywall and stripping paint. You will also see liquid sandpaper, which is used to remove the thin top surface layers of glossy painted items. But determining the right sandpaper for a project is mostly determined by color. With that being said: Marry the paper to the material and the project!

There are two kinds of sandpaper out there: commercial and industrial. You will find commercial sandpaper in your average hardware store. I am mostly concentrating on commercial sandpaper in this article. But it’s important to know that the industrial kind is more often considered an “abrasive.” Although sometimes it looks like regular sandpaper, it’s made from different particles and usually backed with a thin fabric of cotton or polyester to give it longer life. Needless to say, they are more expensive.

Numbers And Letters And Color, Oh My!

One thing to understand about sandpaper is the importance of the number on the backing. This number refers to the grit or roughness of sandpaper. The grit is a universal gage determined by the number of particles applied on each square inch of the paper at the time of manufacturing. The higher the number, the more tiny particles there are on a square inch. Look at it this way: a piece of sandpaper with 100-gage grit has 100 particles per square inch of paper. A piece of sandpaper with 400 grit has 400 particles per square inch, and so on. Sandpaper can go as high as 2000 particles per square inch and even higher.

Now you know about the number, let’s talk about the letter. This can get really confusing. You may feel that there are too many letter combinations. However, the letter refers to the weight of the backing material on the sheet of sandpaper. Generally, “P” refers to Paper backing—in other words P220 means—Paper 220 grit. “P” is most common among papers found in the United States.

Another important difference is the color of the abrasive. You will find sandpaper with black, red, yellow, purple or just plain brown paper-bag color. With modern technologies, many companies like 3M are now presenting new products with synthetic minerals, strong resins, and even special longer-lasting ceramics. Traditionally, sandpapers for woodworking have been made of Aluminum Oxide, Garnet, Silicon Carbide, and Ceramic. Up until recently, the two used most often by woodworkers are Aluminum Oxide and Garnet (identified by the red coloring.) Keep in mind the color usually does refer to something—from brand to manufacturing and it will impact your final purchasing decision so read the labels carefully.

Don’t be pushed away by the new ceramic sandpapers. Ceramic is the hardest of all of the abrasives commonly available. It is also one of the most expensive materials available, but with new technology, you will see it more and more. I encourage you to try it sometime: the sandpaper DOES last longer.

Let’s get to the sanding. As you look at your project you will be determining the finish you want to end up with before you start. This will be a huge factor to determine the sandpaper that you purchase. Generally speaking, you are safe to always have on hand a variety of grits from 150 to 400, usually a 150, 240, 320 and 400. These are standard U.S. grits. Grits outside of this run usually indicate a foreign-made brand.

Why Do You Need So Many Numbers?

In the carpentry world, you will often hear the phrase, “Be sure to run through all the grits.” This means you should work your way toward your finished piece by progressively moving up in grit with the sandpaper. For example, if I start sanding a piece with 150 grit, I have to progress to 240 before I hit it with 320. Skipping a gage of grit will leave scratches behind. The grits are designed to progressively work the piece to an even, smooth finish with each level breaking down the one before. I usually sand to 320 before I start staining or sealing a piece. Depending on the wood I am working with, I don’t want to “over” sand. This is when the pores of the wood become clogged and prevent the stain from penetrating the grains evenly. I usually use 400 grit in between coats of water-based polyurethane. I use 600 to 1500 grit mainly on Venetian plaster.

I leave you with the one cardinal rule in the DIY process of sanding: Always sand with the grain of the wood, not across it. After trying it on a scrap piece of wood you will see how the scratches are visible across the wood, so it won’t make for a very nice finish.

I really hope that by bringing a little insight into sandpaper, more people will see it as a necessary step toward the success of a professional-looking finish. Whether your project is working on a wall, a piece of outdoor furniture or a floor, using the right abrasive will make or break your project.

The Keys To Successful Sanding

The next time you consider using or buying sandpaper, take these things into consideration:

• Marry the abrasive to the material. Sandpapers and abrasives are made specifically for different surfaces—wood, metal, etc.“Follow the grit through”

• ALWAYS go with the grain

• As a safety reminder when working with sandpaper, be it by hand, with a sanding block, or with a portable sander, use your safety glasses and a dust mask.