Sandpaper - the types

Although sandpaper is always similar, there are many differences. After that, abrasive papers can be subdivided into different types according to different criteria. The types of sandpaper you can find below.

The construction of sandpaper

That sandpaper clearly differs, is quite clear to most users. Especially in terms of grain, almost every craftsman and do-it-yourself knows what is meant. But sandpaper is even more special. First, it can be distinguished according to the structure. A modern sandpaper consists of several layers:

  • support material
  • Basic binder (glue)
  • the abrasive grains
  • oversize

The carrier material

The carrier material was formerly mostly made of linen. For sandpaper, which is used for machines, linen is still used. For example, for the abrasive for a belt sander. But even with the sandpaper sheet for the orbital sander this layer today often consists of paper.

Nevertheless, linen should also be preferred here. Anyone who has already used sandpaper with a paper backing layer in the orbital sander knows all too well that the paper breaks very fast on highly stressed areas, even though sufficient grain size would still be available.

The basic binder

The base binder is made of glue or a synthetic resin based adhesive.

Distinct differences in the abrasive grains

There are the biggest differences in abrasive grains. This is also clear from the different names of sandpaper. In addition to sandpaper, sandpaper is often the chosen name because, in principle, sand was formerly used as a grain. Today mainly technical-ceramic products are used as granulation:

  • Aluminum oxide is the most common abrasive grain used with good general properties
  • Boron nitride is almost as hard as diamond and above all extremely heat resistant (more than diamond), which qualifies it for numerous special machine application
  • Silicon carbide is heat resistant, which is why it is preferred for machine use
  • Diamond is the hardest and also more expensive to manufacture because carbon has to be pressed under very high pressures

The ceiling binder

The cover binder keeps the grain on the sandpaper.

The grain

The grit forms a broad spectrum. Not only is the abrasive grain size important, but also its scattering. The further a grain is removed from the other, the deeper it penetrates into the material to be processed. From this concludes: the coarser the sandpaper, the greater the scattering. The size of the individual abrasive grains usually ranges from 20 (very coarse) to 1,000 nanometers (very fine).

On the sandpaper, in addition to the size of the grain, for example, 400, is still a superior letter to see, so for example P80. The letters describe the hardness of the abrasive grain. The ascending letter in the alphabet increases the hardness. The hardships are divided into hard, medium and soft:

  • A to K: soft grain
  • L to O: medium grain size
  • P to Z: hard grain

Now, sandpaper is still differentiated from wet sandpaper and dry sandpaper. Irrespective of this, however, the grain size also defines the typical area of ​​application, here using the example of wood:

Grain size 40 to 120

Sandpaper in these grades is used for beveling and rough grinding. Depending on the material is started with 40 (metals) or mostly 80 (for example wood). Ultimately, this is also a matter of experience.

Grain size 120 to 180

Coarse sanding papers are used to refine the sanding pattern, but may already be the final sanding on some materials.

Grit 180 to 400

Fine sandpaper is the finish when sanding wood.

Depending on the alloy, finer grain sizes can be used to grind metals. So there are abrasive papers ultimately up to the grain size 7000. Common are grains up to 1000.

Tips & Tricks

Here we offer tips for storing sandpaper. In particular with abrasive papers for metalworking, some of the mentioned aspects should urgently be considered.

Video Board: Understanding The Different Grades of Sandpaper