Sandpaper is often used to smooth surfaces, be it wood or metal, and to clean and often shape as needed. Processing with its participation can be done either manually or with the help of special tools or even whole machines, which already depends on the material to be processed and the level of complexity. At the same time, in order to achieve the desired result, it is important to understand what kind of sandpaper to choose for certain jobs.
1. Types of sandpaper
First, although in many situations it is not the most important thing, what distinguishes sandpaper from each other is precisely the base on which the abrasive is applied. In the process of work, this, of course, can fade into the background, but in many respects the strength and durability of the sandpaper depend on it, which is also quite important. Nevertheless, you should not sharpen your attention on the presence of the word paper, since in addition to it, other materials are the basis for the skin. Below we will dwell on each of them in a little more detail in order to understand their main advantages and disadvantages.
Of course, one of the most common and logical (from the point of view of the name) grounds for applying an abrasive is paper. It can be either normal or water resistant. This type of skin differs in that, among others, it is much more affordable, but it also has other advantages. For example, if you need a small piece of sandpaper for work, you can easily tear it off. At the same time, it does not stretch and allows you to easily process a relief surface. It is also attractive in that it makes it possible to apply the smallest abrasive powder. True, this type of skin is consumed faster than the others, especially considering that in places where the paper is broken, the powder crumbles rather quickly. Well, the biggest drawback is the low strength of the paper base.
This material for the base of skins ranks second in popularity and distribution. Of course, in terms of durability, it is much more reliable and practical than paper, but that is why its cost is much higher. This type of sandpaper is really distinguished by its high strength, mainly due to the fact that fabrics (be it polyester or cotton) are pre-impregnated with resin, which also imparts resistance to moisture. Although there is a disadvantage to this, as it becomes somewhat rougher, and the treated surface may not feel so good. And yet, such a skin can gather dust in the closet for years and not lose its abrasive properties. It also has very good elasticity, which is more disadvantageous for machining.
It is logical that this type of sandpaper is based on a combination of fabric and paper that are glued together. In fact, the skin on this basis is the most expensive and less common among home craftsmen, as it is used more in professional and complex tasks. Of course, such a skin has all the advantages of the two previous types, practically neutralizing all their disadvantages.
Skins are also found in the vastness of the modern market on a fiber basis, although in conditions of manual processing they are hardly highly popular. And the reason is pretty simple – they are designed to be used with sanding machine discs. But, among its advantages, one can note the ability to process the hardest surfaces.
The last type of sandpaper, to which, in fact, the previous one is often referred to. As the name implies, such a skin is based on a soft base, which is most often foam rubber or polyurethane. With its help, the final stage of processing of embossed parts made of wood or plaster is carried out, which is extremely practical, since you will need to feel every element of the treated surface.
This indicator in the choice of sandpaper is the most important, since the efficiency of work as a whole depends on it. At different stages of cleaning, skin with different grain sizes is used. It will not be difficult to choose the right one, especially if you know what kind of sandpaper you need, since these indicators are always indicated on the back of the sandpaper. Typically the grit range is 12 to 15,000 grit, although much more can be found in some cases. This number is nothing more than the number of wires per square inch of sieve through which the abrasive was sieved. In a simpler sense, it corresponds to the number of particles of the latter per the same square inch, only found on the basis of sandpaper.
So, the numbers that come after the letter P or the word Grit on the back of the skin are indicators of its graininess. With this sorted out. However, for those who are not entirely aware of how this affects the cleaning process, it is worth talking about this in a little more detail. For example, if you need to clean this or that surface in order to level it, then any sandpaper with a grain size of up to 80 grit is suitable for these cases. It provides a rather coarse sanding, and is mainly used on flat surfaces. Further, in order to eliminate small scratches and depressions at the second stage of processing, it is recommended to use a softer skin, from 100 to 200 with a small grit. True, the upper figure will depend on the material.
For finer processing, for example, preparing wood for priming and subsequent painting, even finer sandpaper is used, over 280 grit. It will allow you to get rid of traces of dust, which in turn can be qualitatively reflected on the surface after painting. The rest of the sandpaper, which is over 350 grit, is super thin and can be used for a variety of purposes where a perfect surface is required. It no longer peels or grinds, it is already used for polishing.
One simple truth follows from this – the higher the grain size of the sandpaper, the smoother the surface to be treated. However, there is also a downside to the coin, since the finer sandpaper grinds off much faster, removing a much smaller layer when processing the material. And in the case of the latter, at the same time, one should not forget about its hardness. In order for the processing process to proceed efficiently, it is necessary to select sandpaper in accordance with these nuances.
3. Type of application of abrasive
When choosing the right sandpaper, this indicator should also be taken into account, since it can ultimately significantly affect the process. The thing is that the methods of applying abrasive powder to the base for the skin are slightly different, and this or that option may be differently suitable for different materials. By the type of application, they are classified as follows:
- Open application (marking – 1);
- Stearate application (marking – 3);
- Closed application (marking – 4).
Application can be carried out by open sprinkling, covering about 60% of the substrate area, which is well suited for crumbling material, since such a skin does not clog so much. For metal, the most common option is sandpaper, where the closed filling method is used, which covers the entire canvas, which, when working with a soft surface, affects the fact that they quickly clog.
With the mechanical method of application, the abrasive particles simply fall under the influence of the force of attraction and do not fall on the base so evenly, on different sides. Another method of application is electrostatic, which allows you to create rather “sharp” skins. The fact is that under the influence exerted by electrostatics, the particles of the abrasive turn with the tip in one direction.
4. Types of abrasive
The abrasive itself is also represented by various amounts of materials indicated in the marking of the sandpaper, and among the most common are the following:
Pomegranate is one of the most popular abrasives for working hardwoods like oak or beech. The main disadvantage of sandpaper with this abrasive is rapid wear.
Silicon carbide is an abrasive used mainly for removing paint, as well as processing metal, plastic, ceramics, granite and other hard materials. Sharp enough, but also quite affordable.
Aluminum oxide is an interesting type of abrasive, characterized by “useful brittleness”. It has a decent service life, since when working with it, the abrasive particles split from mechanical stress and frictional forces, forming new sharp edges.
Diamond is perhaps the most expensive type of abrasive, which is known to be highly durable and sharp. Excellent for polishing cemented carbide materials.
Ceramic abrasive – most often found in the form of sanding belts and is used exclusively in coarse sandpaper, featuring a very high hardness.
Electrocorundum is the most widely used abrasive. Much more durable than aluminum oxide, it has high cutting performance. It is mainly used for the treatment of metal surfaces, but also for hard wood.
Quartz is not the most used abrasive, which, however, is no less practical. Mostly due to the fact that it is used when working with glass (in the same optics) and ceramics.
You can always find all of the above features in the marking of sandpaper, which will allow you to quickly and easily select the desired option. At what, when talking about all the features, then this is exactly what is meant, since there you can find the following characteristics of an abrasive cloth:
- dimensions of the canvas;
- base material;
- abrasive application method;
- type of abrasive;
- fraction size;
- the chemical composition of the glue;
- wear resistance class.
All these characteristics are indicated in the marking, which is an alphanumeric code that encrypts this information. There are a number of special designations used in marking, but for a simple user they will be absolutely unnecessary, since we have listed all the main aspects that deserve your attention when choosing sandpaper.