Sanding a wooden piece of furniture, an essential step in a renovation. Sanding is a simple job, but it quickly becomes tedious if you don’t have the right tools and don’t respect a few basic principles. I have told you about it several times here; one of my activities was to renovate antique furniture. So I am detailing to you step by step how I proceed. I hope that my advice will help you get started to give life back to a wooden piece of furniture!
How to sand a wooden piece of furniture? Waxed or varnished furniture?
Before sanding wood furniture, it is necessary to determine which finish has been applied. Indeed, not all finishes can be sanded. The two main finishes are waxed furniture and varnished furniture. When observation is not enough to decide, there are several ways to know which finish has been applied. A number of the methods suggested are chemical-based, which I personally try to avoid.
I offer you a very simple and non-polluting tip. Simply pass a 120 grit sandpaper over a small area of the furniture already cleaned and observe the result:
- If the paper is clogged with a paste, as in the photo below, it has probably been waxed.
- If the paper remains “clean,” and the sanded surface instead generates dust that does not stick, it has probably been varnished.
Waxed woods cannot be sanded; you would only succeed in clogging the sandpaper and “spreading” the wax by heating it. You will therefore have to remove the wax from the piece of furniture beforehand. The varnish can be sanded very well!
How to sand a wooden piece of furniture? Identifying the different woods and the manufacture of the piece of furniture
To know how to sand a piece of wood furniture properly, you need to look at how it is designed, including the type(s) of wood used. There are several techniques to obtain this information, and I share with you a very simple and often the most effective one, which is to turn the furniture over. This allows you to see the inside of it, which is very instructive. Once we know what type of support we will have to sand, we can make the right gestures and use the right tools!
On this piece of furniture, we can see that several types of materials were used in the photos below:
- Solid wood for the uprights (photo on the left): by observing the slices, we can see a logical continuity between the wood fibers on the different faces. We can see that it is, therefore, “one-piece.” Here, the wood used is oak.
- Plywood for the furniture panels (photo in the center): the top and the sides. Plywood is often used for this type of furniture because it is less expensive and significantly lighter. This allows having a thin and resistant board thickness at the same time. It is composed of several thin plates or sheets of wood glued together perpendicularly. The direction of the wood fiber is reversed by superimposing the layers for more resistance.
- Veneer for the sides and top (photo on the right): it is a skinny sheet of wood (often less than a millimeter for antique furniture) glued on wood or plywood. If we look at the outside furniture, we can see that the top and sides’ aspect is identical to the uprights and drawers. As we saw when turning the furniture over, these elements are made of plywood, so it can’t be solid wood: oak veneer was therefore used and laid on the outside faces.
How to sand a wooden piece of furniture? Before you start
To sand a wooden piece of furniture, place it on wedges to raise it slightly (simple wooden strips are acceptable). This will allow you to sand the bottom of the furniture easily.
If your sander has a field vacuum connection, use it! You will breathe less dust, and sanding will also be easier because the dust will not remain on the parts you are working on. If you are a regular DIYer, I think this is the best investment you can make! By the way, it has become my household vacuum cleaner. I find it much more efficient than household vacuums 🙂
How to sand a wooden piece of furniture? The first sanding of large surfaces
Obviously, the main element for good sanding is the sander! Here you can find out about the different types of sanding machines to use and make your choice. I always start sanding with large flat surfaces. Here, the plate and the sides.
For sanding solid wood: this is the easiest to sand. Because of its resistance, one can afford to remove some material and go a little “in force.” I use a coarse grain for this type of sanding (60 or 80 depending on the “tenderness” of the wood), the turbo function of my sander, and a high speed.
For sanding veneer: sanding veneer is much more delicate. In fact, there is a risk of either peeling off the sheet or removing too much material and revealing the plywood underneath. I sand the veneer with a medium grit of 120 maximum (and I advise you to start at 180 and see if it’s enough), with a low speed if you have a dimmer. The goal is to remove as little material as possible. If you are sanding with an eccentric sander, put the pad on the wood and then start the sander.
For this step, several passes may be necessary. The goal is not to obtain a nice finish but to roughen and expose the wood. If you wish to paint your furniture afterward, you can sand the surface: the idea is to remove part of the finish and scratch the surface sufficiently to adhere to the undercoat of paint. If you wish to leave the wood visible, a more meticulous and in-depth sanding is necessary to recover a beautiful uniform wood.
How to sand a wooden piece of furniture? The first sanding of angles and grooves
The eccentric sander is not suitable for sanding corners, edges, and parts such as drawer rails or moldings. There are 2 solutions for this: the triangular head sander and hand sanding.
The triangular head sander:
For corners or parts that are more difficult to access, I use a vibrating triangular head sander. Here my eccentric sander turns into a vibrating triangular sander by changing the soleplate. I also use it for sanding curved parts. If you don’t have one, you can, of course, be satisfied with manual sanding.
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Sanding by hand:
For the rest, I sand by hand! I use cloth sanding paper, which can be folded and curved without tearing. I fold the paper in half for the moldings, stretch it with both hands, and “slide” the paper into the grooves. Remember to vacuum regularly or remove dust with a cloth while sanding.
How to sand a wooden piece of furniture? Finishing sanding
Once the entire piece of furniture has been sanded and the original wood exposed, it is now necessary to refine the sanding for a nice uniform finish. I then re-sand the furniture with a finer grain by repeating steps 3 and 4. For this step, touching wood is essential: this ensures that no spot is forgotten. You will see and feel the difference under your palm: the wood becomes smoother and softer.
If I started with an 80 grit, I go back to 120 grit, then to 180 and 240. If you’re going to paint the wood, you can stop with 180 or 120 grain. Indeed, the undercoat will stick to the wood, and when you apply it, the wood fibers will spike. It will then be necessary to sand with a finer grain (240) between coats to regain the “softness” of the wood.
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After all these steps, the sanding of your furniture is finished! All you have to do is carefully dust it off with a vacuum cleaner and a slightly damp cloth, and proceed to the painting or finishing step. If you wish to leave the wood visible, I advise you to apply a finishing oil.