Sanding 101: How to Become a Sanding Expert

June 16, 2017

Getting started is the hardest part of any project. But for woodworking, it's actually quite simple. Grab some sand paper and try your best to avoid making a huge mess. However, there are so many different kinds of sandpaper. Which leaves us with this question. Which type of sandpaper should you use?


Choosing the Right Grit

Sandpaper works by scratching away defects with thousands of tiny abrasive particles. The lower the number, the coarser the grit; and the higher the number, the finer the sandpaper. Most homeowners will never use grits at the top or bottom of the scale.

Sandpapers are commonly graded as:

Extra Coarse  (12-24 grit): Very uncommon to be used for a homeowner. Used for very rough work, heavy machines, wood floors, etc.

Coarse (30-50 grit): A good choice for rough sanding and removing stock quickly, such as sanding the edge of a sticking door with a belt sander.

Medium (60-100 grit): Makes a good starting point for most projects, from sanding unfinished wood to removing old varnish.

Fine (120-180 grit): Great for removing the scratches left by coarser grits on unfinished wood and for lightly sanding between coats of paint.

Very Fine (220-300 grit): Used for light sanding between coats of finish and to sand metal and other hard surfaces.

Extra Fine (320-400 grit): Same as very fine, unlikely to be used for a homeowner.

Super Fine (400+ grit): Same as very fine, unlikely to be used for a homeowner.

*Note: Sandpaper is graded commonly graded by CAMI and FEPA. Numbers will vary.


Types of Abrasives

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.


But wait… There's More!

You may see sandpaper that is called "open-coat" or "closed-coat".

"Open coat" papers have more space between each abrasive particle, so they don't clog as quickly with dust. Coarse grits are typically open coat.

In grits finer than 150, where clogging is less of a problem, most sandpapers are "closed coat," covered completely with abrasive. Hardwoods and metals can be sanded with closed-coat papers.

As a general rule, open-coat is typically better for woodworking, as it clogs less often, particularly when working with softwoods like pine.  


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.

If you want even more information and details, check out these helpful sites. See you next Friday! 

The Spruce, LowesHome Fixed, The Engineering Toolbox.

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