Sanding

Adding the finishing touches

Sanding is usually one of the later steps in woodworking, but it is also a very important one. It plays a particularly significant role in furniture making, as it is a decisive factor in the overall appearance of the finished piece. Even if you prefer to smooth wood surfaces with a finishing plane and scraper, you will achieve the desired high-quality result by applying layer-forming surface treatments followed by re-sanding, fine sanding and, if necessary, ultra-fine sanding. In other areas of woodworking, too, workpieces are usually sanded as a final step and not left rough-sawn or plane-smooth.

Manual sanding

Although sanding by hand is labour-intensive and the results are not always as consistent as desired, sometimes it cannot be avoided. In such cases, you should always use sandpaper with a sanding block to avoid unintentionally rounding off workpiece edges or sanding indentations into wooden surfaces. For this purpose, Festool sanding blocks are available with extraction connections for connection to workshop vacuum cleaners, so that you do not have to expose yourself to the risks of sanding dust even when sanding by hand.

Electric sanders

In most cases, you can achieve your goal faster with less effort by using electric sanders. There are three types of hand-held sanders:

•Belt sanders are ideal for rough and preliminary sanding, for quickly removing large amounts of material and working on large surfaces. However, if you equip a belt sander with fine sandpaper and sand in the direction of the grain, it can also be very useful for fine sanding (especially long) workpieces.

•Orbital sanders are often colloquially referred to as sliders. They have a sanding plate to which the sandpaper is attached. The sanding plate is rectangular, which makes it easier to work close to edges and corners. A variant with a triangular sanding plate is called a delta sander and allows sanding even in very tight corners.

•The random orbital sander is a further development of the orbital sander or the manually operated disc sander, which is hardly ever seen anymore. It has a round sanding plate. It not only oscillates, but also rotates. Although material removal is lower than with an orbital sander, the surface quality achieved is correspondingly higher . This is why the random orbital sander is the tool of choice for fine sanding.

Stationary sanding machines

Workpieces with internal curves are difficult or impossible to sand with electric sanders. For this purpose, it is better to use a spindle sander. It can be equipped with spindles of different diameters, so that small and large curves can be sanded equally well. In addition to the oscillating spindle sander from Triton, we also offer a combination machine (oscillating spindle and belt sander) from the same manufacturer, whose belt sanding unit is particularly suitable for stationary sanding of workpiece edges. Various stationary sanding machines are used in carpentry workshops, but their purchase is almost never an option due to their size, acquisition costs and operating costs.

How do you sand wood correctly?

The basic procedure for sanding is the same regardless of whether you are working manually or with a sanding machine. The material you want to sand also plays only a minor role (more on this below).

When sanding wood, choosing the right grit size for the abrasive is crucial. This is indicated by a number that is proportional to the number of abrasive particles embedded in a specific surface area of the backing. This means that with higher grit sizes (larger numbers), the size of the abrasive particles decreases, making the abrasive finer. Abrasives with grit sizes ranging from 60 to 320 are commonly used for woodworking. However, grit sizes outside this range may be necessary for certain specialised tasks. The following table can be used as a guide:

Grit sizes for sanding woodGrit sizeUseSandingup to 60Sanding off old layers of varnish and other residuesCoarse sanding60Pre-sanding solid woodCoarse sanding60 - 120Sanding milled and planed solid wood surfaces; Sanding veneered surfacesPre-sanding120 - 220Sanding solid wood, veneered and water-treated surfacesPost-sanding220 - 320Sanding solid wood and veneered surfacesFine sandingover 320Sanding primed, intermediate-coated and final-coated surfacesUltra-fine sanding

The table clearly shows that sanding usually has to be carried out several times in succession, using increasingly finer abrasives. This is because every abrasive leaves marks on the surface, which are sanded out in the subsequent sanding process until the desired surface quality is achieved.

For solid wood and veneered wood-based panels, fine sanding is always carried out in the direction of the grain, as sanding across the grain causes slight sanding marks.

Safety when sanding

Sanding wood produces sanding dust, which is extremely hazardous to health. This is particularly true for types of wood that contain toxic or carcinogenic substances (such as oak and many exotic woods). As the fine dust can penetrate deep into the lungs, it is essential to ensure good dust extraction using an industrial vacuum cleaner. For your own protection, you should also wear a respirator mask or similar. Many users also wear safety goggles to prevent eye irritation.