How To Use Sandpaper Like A Pro

Sandpaper, or glasspaper, has been around since the 13th century, when China used crushed shells, seeds, and sand, glued together with natural gum, to form an abrasive material. Since then, this common tool has taken many shapes and materials, evolving and improving each time and becoming an essential utensil for DIY projects and woodworking.

Now, even though it’s a fairly easy-to-use tool, the lack of knowledge on how to use sandpaper, its different types and various grit values can be the decisive factor between a beautiful, smooth table and a rough nightstand with marks and scratches all over. That’s why we’re here today to give you some pointers, regarding this tool and how to use it correctly.

Grit Values

First things first: What does the grit value mean? It refers to the coarseness of the tool in hand, i.e., the size of the abrasive particles. If you’re in the United States of America, the grit will be based on a scale called Coated Abrasive Manufacturers Institute (CAMI), that uses microns to measure it - the small grains on a piece of 100-grit measure 141 microns and are equivalent to 0.00550 of an inch - that small! Don’t forget to take into consideration that if you’re buying online from Europe, you’ll be working with the Federation of European Producers of Abrasives (FEPA) scale, which has some small differences.

Now, because most people use the CAMI scale, that’s the one will refer to. This scale goes from 24-grit to 2000 and beyond, even though the ones above 1000-grit are mainly used for automotive finishing. For house-hold projects, we recommend working with numbers between the 60 and 220-grit. Remember, the lower the number, the more material removed, but also more noticeable scratches; the bigger the value, the more effort in removing material, but a more polished appearance. These numbers will, most of the time, appear on the back of the paper.

The number one rule when tackling projects that need sanding is to work your grit over time, meaning you should start with a finer one (bigger grit value) and work your way to a more coarse one (lower grit value). Not following that rule can result in over-sanding details, leaving the surface too rough, or making you put an excessive amount of effort. Now, some grit values excel in some tasks, so here’s a guide that will help you choose the best one for your project:

60 to 80-grit: Being the roughest, it can, pretty effortlessly, shape wood and round edges, as well as cut through old paint and rust. Not recommended for fine details, or plywood, as it can sand through its thin face layers, pretty rapidly. Also used for sanding old, worn-out flooring.
100 to 150-grit: This is the most versatile and widely used grit, as it's pretty hard to screw a project with it. On one side, you can press harder and shape objects while, on the other side, you can press gently and remove scratches while preserving finer materials. If your goal is to paint a wooden item, a final 150-grit sanding is ideal, helping the paint to better grip the surface.
180 to 220-grit: We don’t recommend starting your sanding with this one unless the object’s surface is already pretty smooth. Perfect for removing raised wood grain fibers or if you’ve already painted one time and are looking to go for a second coating.
320-grit and over: This is the all-time grit for smoothing and can be used on various materials (wood, plastic, metal, etc…). You’ll see some of these ones used for wet sanding, creating a fine grainy slurry, resulting in a better smoothing.

Types of Material

As we’ve mentioned before, we’ve come a long way since crushed shells and seeds - thankfully! Even though all materials used are abrasive, there are small differences between them and knowing that will definitely improve your DIY skills, as well as the overall aspect of your projects!

Natural

Garnet is a natural grain made from silicate minerals. It’s softer than flint and emery and is mostly used in hand sanding. If you want to prepare the surface for finishing or removing simple scratches in raw wood, this is the tool to get. The big advantage is that, due to the abrasive particles breaking during use, you’ll always get new edges in it’s surface - that also means it wears quickly!
Flint is a sedimentary form of quartz. Its main advantage consists of high durability and its primary use is for sanding old varnish or pain.
A dark granular rock, called emery, can be used for hand sanding, as well as power sanding. You’ll see a lot of factories removing corrosion from metals with this, even though it also does a pretty good job in sanding wood.

Synthetic

Aluminum oxide is, as the name states, the mix between aluminum and oxygen. This blend forms an abrasive material and, probably, the most used sanding tool, worldwide. On one side is highly durable while, on the other side, highly versatile, as it can be used in a variety of materials, like wood, plastic, metal and drywall, as well as in both hand sanding and power sanding.

Next up, we have silicon carbide - a semiconductor material made of silicon and carbon. A plus over the latter one is its capacity to remove material quicker and more effortless, even though it won’t last as long. Usually used for rough sanding and paint or rust removal, you can add water to the mix to prevent scratching, as it's waterproof. It can also tackle various materials, like plastic, metal, hardwood and softwood.

Lastly, there’s the zirconia alumina. A synthetic material, made from zirconium dioxide and aluminum oxide, that excels in grinding metal burrs or rough sanding wood. It’s one of the most durable ones and like the last two, its particles break during sanding, meaning it can maintain its coarseness over time. Mainly used in power sanding, it can work with wood, fiberglass and metal, even though it really shows its talent with painted surfaces.

Tips on How to Use It Like a Pro

Still to this day, there’s a lot of people who use sandpaper by itself, wrapped around a sanding block (a piece of cut-out foam, a wooden block, a block of cork, etc...) but you’ll see the work cut in half - both in effort and in time - if you mount it on a power sander. Among all types of power sanders, palm sanders are likely the most popular for beginners due to their ease of use, versatility and really affordable prices. If you would like to check out a list of the best ones on the market, right now, click here.

How to use sandpaper might look like a question with a pretty simple answer - just rub the sander on the surface, right? Well, even though that’s the gist of it, here are some guides and tips that will help you reach better and more polished results:

If it’s your first time using a new sanding material or a new power tool, we recommend starting on scrap wood, similar to the one you want polished, so you can get a feel of how much material it actually removes
When working your way through different grit values, don’t skip one, as you’ll have to spend more time and effort in the next one.
When compared with hand sanding, power sanding requires much slower movements, without any sudden changes of speed and direction. Also, no need to press down, let the sander’s weight do the work, instead!
Before changing your grit and start sanding again, remember to clean off loose abrasive pieces and dust of your item - you can vacuum or just wipe it down.
Sand all edges in these situations: between coats of paint; after cutting; before applying a finish.
Always sand with the wood’s grain, not against it! This way, all the scratches will be much less visible and your piece will have a better overall appearance.

Final Thoughts

Now that you’re much more informed on how to use sandpaper, nothing is standing between you and a pleasant afternoon of DIY projects. You’ll see the difference a bit of polishing can do to some boring furniture or a worn-out floor when your frequent guests will ask you: “Hey, where did you get that new table? It’s fantastic!”. Thanks for reading and, as always, have a great day!

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