If you’re a hardcore do-it-yourselfer like me, you’ve likely tried to refinish some furniture, or re-purpose old wood to new uses. Regardless of what your project is, sanding your wood is the most important step towards creating a finished piece. It removes old finishes, smooths out scratches and gouges, and ensures a smooth surface under your finish. These tips will help you get a well-sanded, flawless piece.
Tools you’ll need:
- Power sander or sanding block (for help in choosing the right sanding tools, click here)
- Appropriate sandpaper (coarse to fine grit, fitting the tool or block you’re using)
- Ear protection (when using a power sander)
- Dust mask
Stripping off an old finish.
For refinishing, I prefer stripping the old finish off by sanding instead of using chemical removers, because I often don’t know what the existing finish is and I don’t want to try solvents that may or may not work. Home renovation guru Bob Vila says that sanding works to remove just about every finish. He warns that paint and varnish strippers have some dangerous fumes that can damage your eyes and lungs, though they are effective. However, he says that if you know you’re removing shellac, solvents like denatured alcohol will work just fine, and don’t contain those dangerous fumes.
To strip finishes with a power sander, I like starting with 60 or 80-grit sandpaper on a finishing sander. In my experience, these rough papers will also quickly smooth out any deep scratches, scars or gouges on the the wood at the same time they’re stripping the finish, which saves time and effort. These low-grit papers leave the wood very rough, though, so you’ll need to work your way up to 150-grit before doing the finish work. I prefer this sequence: 60, 80, 120, 150, 220.
On the other hand, I’ve found that new wood from, say, Home Depot, doesn’t need much work. I usually lightly sand these pieces by hand, with 220-grit paper, to remove the mill marks. I avoid using a power sander on moulding, though, because even with fine papers, I’ve found that it can damage the moulding’s profile.
Note: All of this applies to solid wood. If you’re working with veneered plywood, starting with anything rougher than 150-grit means you risk sanding through the veneer. For more on the differences between sanding solid wood and sanding veneered plywood, check out this article from “Popular Woodworking.”
How finely you sand your wood depends on the finish you want to use.
How fine you should sand it it depends on what finish you’re using, according to the “Popular Woodworking” article. For film-building finishes such as polyurethane, lacquer and shellac, sanding above about 180-grit can be a waste of time, because these finishes build their own surfaces. Therefore, the smoothness of the piece depends on how well you apply the finish, not how finely you sand the wood. You’ll want to do the final sanding by hand, though, to avoid having tiny cross-scratches brought out by the stain or finish.
However, if you’re using finishes like tung oil, an oil-varnish blend, or any finish that doesn’t leave a definite film, and you want an ultra-smooth texture, you should sand it in steps all the way up to 600, or even 800-grit, paper. You will also need to sand each coat after it cures to maintain the smooth texture.
Finally, I find that using both my eyes and my fingertips works very well for finding flaws that should be sanded out before moving on to the next finer sandpaper. Using both senses, instead of just one, has proven to be far more effective when it comes to making sure my wood is flawless before I finish it.