Types of sandpaper

The sanding task consists of the application of an abrasive element on a surface to polish or smooth it through continuous rubbing, eliminating the peaks or roughness that the surface could present, leaving a uniform surface. To achieve this result, different kinds of tools, among which the sandpaper It is the most used item.

Origin of sandpaper

The sanding process dates back to 4,000 years ago, when sand was used for polishing in the Middle East. Initially loose sand was used, which was spread over the surface to be polished and rubbed repeatedly with a piece of wood or leather.

The sandpaper known and used today, it originated in the year 1400 in Switzerland, where crushed glass was adhered to paper to obtain an abrasive material. The sandpaper It arises from the simple sandblasted cardboard that, over time, gave way to different varieties of this very useful tool.

Sandpaper composition

The sandpaper It consists of two parts joined by an adhesive.

The support: It is a sheet of paper, cloth or fibrous material that must be strong enough not to break easily during sanding, which involves rubbing this paper on the surface to be polished. For sand wood sand usually use sandpaper with a paper or cardboard support, while for metal sanding the support is made of resistant fabric or fiber. The support is manufactured in the form of sheets or handy rectangles for small jobs.

granular surface: On one of the faces of the sheet that serves as a support, granular material of different types is adhered, according to the required grain size and the type of polishing, for which greater or lesser hardness of this material may be necessary. The granular abrasive element can be made of silicon carbide, aluminum oxide (a variety of which is emery) or zirconium.

• Silicon Carbide Surface: This is an angular grain, low in toughness and low in durability. It is mainly used to sand solid materials such as: stone, marble, titanium, glass, fiberglass, lacquers, ceramics, rubber or plastics.

Silicon Carbide Surface Sandpaper

• Aluminum Oxide Surface: This is a round grain, which has toughness and is highly durable. It is the one for sand materials such as metal and wood. as well as for sand walls plastered.

Sandpaper with aluminum oxide surface

• Zirconium corundum surface: this is a grain with great uniformity, great toughness and very long life. It is ideal for sand stainless steels.

Abrasive with zirconium corundum surface

How to use a Sandpaper

The sanding of a surface is carried out by means of longitudinal manual movements on it, in such a way that the granulated part of the sandpaper rub the area to be polished. In the case of wood polishing, the movement must follow the direction of the grain. On small surfaces it will suffice to press the smooth face of the sandpaper with your hand on them. To exert greater force and in a more uniform way, a flat piece or wooden block can be used to help exert the necessary pressure. In addition, there are electric sanders, in which the sandpaper It is attached to a disk that, when rotating, performs the work on the object with greater efficiency and speed.

Types of Sandpaper

The grain size of the sandpaper used depends on the material to be sanded. In such a way, there are sandpaper coarse, intermediate and fine grain. Also, the choice of the granulate of the sandpaper It depends on the quality of the required termination. sandpaper thick will give a rustic finish, while sandpaper fine will allow a more delicate polishing. On the other hand, it is possible to perform wet or dry sanding. Both possibilities have specific advantages according to the material to be treated.
The grain size of a sandpaper is called or known by the grain number. The lower the grit number, the larger the grit size, and therefore the coarser the sanding. For quality sanding, it is recommended to use several sandpapers, starting with the coarsest and moving towards the finest. Types of sandpaper according to the grain number:

• Coarse sandpaper: the sandpaper with coarse grit, they are used to start work on very rough, rusty surfaces or to remove adhering paint, before final sanding. This type of sandpaper covers the following numbers: 80, 60, 50, 40, 36, 24, 20, 16, 12.

coarse sandpaper

• Medium sandpaper: the middle grain of a sandpaper It is efficient to improve the finish of a surface that has been previously treated with sandpaper gross. Once the paint or rust has been removed, or the wrinkles have been smoothed out a bit, the sandpaper medium grain smoothes the piece to be polished before its final treatment. This type of sandpaper covers the following numbers: 280, 240, 220, 180, 150, 120, 100.
• Fine sandpaper: the sandpaper fine-grained achieves a smooth finish on surfaces. However, it is required to use sandpaper thicker ones on areas that are too rough, since doing the work directly with a sandpaper fine, the task would be too hard, take too much time and probably not give the expected results. sandpaper covers the following numbers: 600, 500, 400, 360, 320.

fine sandpaper

• Extra fine sandpaper: this sandpaper is used to remove the roughness that may remain after the work is finished. This type of sandpaper covers the following numbers: 1500, 1200, 1000, 800.
• dry sandpaper: the sandpaper for dry polishing are the most common and can be used on all materials, with different results. One of its problems is the emission of dust, for which it is advisable to use protective glasses and a mask during sanding.
• Water sandpaper: the sandpaper to water can be used in the same way as sandpaper dry, or immerse in water for use. They are more efficient for the elimination of residues and to give a better finish on certain materials.

water sandpaper

On the other hand, it is also possible to classify sandpaper in sandpaper with open grain and with closed grain. The sandpaper with open grain, they have fewer grains per surface unit. The opposite occurs with the sandpaper closed grain. The open-grained ones are ideal for paints, putties, soft and resinous woods, plasters, wet or dead plaster, among others.

open grain sandpaper

We can also find the sandpaper With a wax-like coating, which allows sanding dust to be evacuated in a much better way, preventing the sandpaper from clogging. This coating is possessed by special sandpaper for lacquers or paints.

Selection of the type of sandpaper

Considering the great variety of types of sandpaper that exist, it is very important to select the most appropriate for the work to be carried out, and also to consider the different phases or stages of the work, if applicable.

We will indicate some examples of applications of the sandpaper:

For the initial removal of excess paint and grainy residue on wood or plaster, a sandpaper coarse-grained dry Once the surface is smoothed, it continues with a sandpaper median and termination is performed with sandpaper dry very fine.

For metal sanding, use the sandpaper emery cloth and follow a similar sequence. Coarse emery for rust and burr removal, then medium and fine emery.

The sandpaper Water-based, in its three grades of granules, is very good for smoothing surfaces filled with putty or to improve the finish of paint.

This useful and efficient tool is a great ally to obtain jobs with perfect finishes. Just choose the sandpaper properly and apply it correctly.

With the application of technology, tools known as sanders have been developed, which facilitate traditional sanding work and come in different models such as orbital sanders and belt sanders, among which you can choose depending on the task to be performed.