Sandpaper & Abrasives

While it may seem like the most straightforward, simple aspect of your home improvement projects, sanding is a crucial step in achieving a high-quality finish. Trying to find the right sandpaper for a given job isn’t always easy, however. While sandpapers may look similar to one another, they are often composed of different materials, feature a wide range of grits and are best suited to certain surfaces. Knowing how to tell them apart and understanding what characteristics to look for will help you select the right sandpaper for the job at hand. Keep the following questions in mind as you shop:

• What materials can sandpaper be made from?
• What does sandpaper’s grit number indicate?
• What surfaces do different sandpapers work best on?
• Aside from sandpaper, what other abrasive tools are available?
• How can you achieve the smoothest, most flawless finish?
  
  

Sandpaper, Other Abrasives and Sanding Tips

One of the more interesting facts to note about sandpaper is that it doesn’t actually contain any sand. While sand was once used as an abrasive material, it has long since been replaced by better natural abrasives, such as garnet, and synthetic abrasives, such as aluminum oxide. In addition to sandpaper, abrasive alternatives like steel wool come in handy for a wide range of tasks from smoothing to cleaning. The material you’re working on will largely determine the best type and grit of sandpaper or other abrasive material to use. Sanding may not be the most exciting activity, but rushing through the task can seriously impact your finish.

Sandpaper: Prior to selecting sandpaper, it’s important to understand the many options available. There are three primary characteristics that determine the effectiveness of sandpaper and when it should be used: grit, whether it has an open or closed coat and what material it’s made from. Grit is a measure of how many particles on a piece of sandpaper could pass through a filter that’s one square inch in size. The lower the grit number, the coarser the paper. For example, a grit of 30 would be very coarse and used at the beginning of a sanding project while a grit of 220 is very fine and would be used in the final phase. Grit numbers can go as low as 12 and as high as 600, but most of the paper you’re likely to need will run somewhere from around 30 or 40 to 220. Coating indicates how dense the abrasive material is on a piece of sandpaper. Open-coated sandpaper has abrasive material covering approximately 70% of its surface, leaving room for sawdust to build up, which helps prevent clogging. Closed-coated sandpaper is completely covered by abrasive material. The following chart details the various types of materials sandpaper is often made of and some of their characteristics.

Material	Description	Uses/Points to Consider
Aluminum Oxide	Synthetic material that is either tan, light gray or grayish brown in color.	Works well for all types of sanding Good for use with a power sander Friable surface sharpens itself as you sand to provide longer life Ideal for raw wood, hardwood and metals
Ceramic	Synthetic material that is generally reddish-brown in color.	Extremely hard and durable Ideal for use with power sanders May be more expensive Ideal for rough sanding
Flint	Beige-colored natural material that is used somewhat infrequently these days.	Economical Not particularly durable Best for rough work on small projects
Garnet	Reddish or golden brown in color. Natural material that wears somewhat quickly, though it provides a finer finish as it wears.	Excellent for hand sanding Coarse paper wears down to provide fine finishes Features a soft grit May be used with all types of woods Economical
Silicon Carbide	Synthetic paper that is blue-gray, black or charcoal in color. Often features a waterproof backing.	Can be used on wet or dry surfaces Less likely to clog than other types Friable surface will self-sharpen on harder materials, like metal Ideal for polishing or using between coats of finish Sharp and durable Ideal for use on metal, plastic, fiberglass and more

Other Abrasives: Sandpaper is not the only material that comes in handy for surface-altering tasks. Steel wool is ideal for removing grime and sludge from a variety of surfaces prior to finishing. It’s also useful for removing old coatings of paint or finish on wood. Like sandpaper, steel wool is graded on a number scale that determines how coarse or fine it is. In this case, it’s rated from 0000 (very fine) to 4 (very coarse). Fine steel wool can be used to scuff sand between coats of finish. If you need to sharpen chisels, knives or other tools, look for diamond stones and water stones. Scrapers are steel cutouts that can be used to finely shave wood. Abrasive sponges are ideal for working in corners or on oddly shaped pieces that conventional sandpaper can’t conform to.

• Use steel wool to prepare new surfaces or between coats of paint or finish
• Steel wool can be used to remove paint from glass, furniture, tile and more
• Water stones use water instead of oil for lubrication, preventing oily residue from accumulating on tools
• Two-handled scrapers allow for more even shaving
  
  

Tips: One of the most important things to remember when sanding is that you should always sand with the wood’s grain, not across it. In most cases, you’re going to need to sand multiple times, so be patient. Start with coarse paper and gradually work your way up to finer sandpaper. Coarse grits can be used to remove large imperfections while medium grits are better for small-to-moderate surface flaws. In many cases, using a fine grit around 180 or 200 will provide the final step, though you may need to touch things up with a 220 grit. Be sure to clean the work surface when you change to a new grit as debris from earlier sanding can interfere with the smoothing process. Where possible, use a sanding block. The block will allow you to apply more even pressure than you can with just your hand, resulting in a better finish. Open-coated paper is ideal for use with softer woods while closed-coated sandpaper is best for metals and hardwoods.

• Various surfaces may require four or more stages of sanding
• Sand in only one direction on end grain to avoid clogging pores
• Finer grits create lighter finishes
• Work in a well-ventilated area to minimize the presence of dust and debris
• Consider wearing a mask or respirator to protect your lungs
• Higher grits may be needed when sanding brass and other metals
• Don’t press too hard, simply let the sandpaper’s surface do the work
  
  

Features

Tack Cloth: In between sanding, you’ll need to clean dust and debris from the surface you’re working on. A tack cloth is a sticky piece of cheesecloth that picks up dust more efficiently than wiping a wet cloth across the surface. Wet cloths can also raise the wood grain, making the surface more difficult to stain.

Rubber Cement Blocks: In addition to cleaning the surface you’re sanding, you can also clean the sandpaper you’re using to help prolong its life. Rubber cement blocks are pressed against the surface of sandpaper, where they remove wood particles that inhibit sandpaper from doing its job.

Safety Equipment: Sanding can kick up quite a bit of dust, so it’s a good idea to wear goggles and use a dust mask or respirator. If you’re working with a power sander, gloves are always a good idea, and make sure you’re not wearing loose-fitting clothing that can get caught in the machine.

Power Sanders: While hand sanding will work well for a lot of jobs, some are simply too big. In those cases, consider using a power sander or belt sander. You may also want to utilize an orbital hand sander, which can make smaller jobs easier.

Zinc Stearate Coating: Some sandpaper features this soapy substance, which is used to prevent clogging. While it shouldn’t be used on surfaces with water-based finishes, sandpaper with this coating will require less maintenance. 

Drywall: When working with drywall, look for drywall sheets, which can be die cut to fit most drywall sanding tools. These sheets are specially made to smooth drywall surfaces and provide long-lasting performance. Drywall sponges fit comfortably in your hand and are reusable. Most feature two sanding grades and are ideal for use in corners and tight places.