SANDPAPER 101

When getting started with a project you will probably need to use sandpaper at some point. However, with so many different kinds of sandpaper, which type of sandpaper should you use?

The Nitty-Gritty: Choosing the Right Grit

Sandpaper works by scratching away defects with thousands of tiny abrasive particles. There are two major sandpaper grit numbering systems used in the U.S.

The first and most common is the system known as CAMI. With this grit numbering system, the lower the number, the coarser the sandpaper grit; and the higher the number, the finer the sandpaper grit.

The second most common (and what we use at Mohawk Finishing Products) is the European, or FEPA numbering system. The best way to identify the difference is that the grit number begins with the letter P before the number. These numbers also go from coarse grit as the lower number and gets finer as the numbers increase.

The numbering between the CAMI and FEPA system is identical (180 =P180) until the grit number 240. After 240, the FEPA numbers change and go higher than the CAMI numbers.

Very uncommon to be used for a homeowner. Used for very rough work, heavy machines, wood floors, etc.

A good choice for rough sanding and removing stock quickly, such as sanding the edge of a sticking door with a belt sander.

Makes a good starting point for most projects, from sanding unfinished wood to removing old varnish.

 Great for removing the scratches left by coarser grits on unfinished wood and for lightly sanding between coats of paint. 

Used for light sanding between coats of finish and to sand metal and other hard surfaces. Same as very fine, unlikely to be used for a homeowner. 

Same as very fine, unlikely to be used for a homeowner.

Same as very fine and extra fine, unlikely to be used for a homeowner.

There's More Than One?: Choosing the Right Type

There are six main types of sandpaper, and they all have various uses.

Garnet: Best used for hand sanding. Suitable for sanding bare wood. Dulls quickly.

Emery: Excellent for hand or power sanding metal. Can also be used to polish metal. You can often find Emery sandpaper on flexible cloth backing.

Ceramic: Used primarily on belts and discs for power sanding. Used for aggressive material removal on wood.

Silicon carbide: One of the best types but wears fairly quickly. Has many uses, including wood, plastic and metal. Can be used for wet sanding.

Aluminum oxide: Common sandpaper. Great for power or hand sanding on wood, paint, drywall or metal. Lasts longer than most.

Zirconia alumina: Suitable for wood, fiberglass, metal and painted surfaces. Typically used with belts, pads and discs for power sanding. Lasts decently long.

Will This One Work?: Choosing the Right Shape and Size

Sandpapers come in various shapes and sizes for different uses and applications.

Sheets : Sheets usually come in 9 x 1 inches. However, other sizes may be available.

Belt : These are created for use with belt sanders.

Disk : These are made to fit disc and orbit sanders.

Rolls: Used by some contractors.

Sponge: These are for tight, small or unique spaces. Most sponges come with a different grit on each side for convenience.

Tips and Tricks

• If it looks bad-it probably is. This same principle applies to your hands. Run your hands over what you are sanding. It is amazing what you can feel that you cannot necessarily see. Working with wood is about as much feel as it is sight.
• Sanding with the grain of the wood is generally preferable to sanding against it. You can definitely take more off if you are sanding with power tools by going cross-grain-but if you are hand sanding, with the grain is the way to go.
• For really odd-shaped edges, make some sanding sticks. Choose differently shaped dowels and attach sandpaper to them with staples or double-sided tape.
• The golden rule of sanding is to start with a grit coarse enough to quickly remove surface imperfections and follow with incrementally finer grits. Each successive grit erases the scratches of the coarser one before, until the scratches themselves become undetectable to the eye and the touch.
• Sponge-backed sandpapers are helpful when working with pieces that have round or uneven edges.
• After sanding your woodworking project, you need to remove all traces of sawdust before you're able to apply the paint or stain finish of your choice.