Grinding gypsum plaster: with which grain?

Once the plaster wall is dried, it can be ground. Only then is a completely smooth wall surface to achieve. Serrants of different grains are available for the finish. They need to be tailored to the desired end result.

Fine abrasives for gypsum plaster

The different qualities of abrasives are mainly based on the grain size. The grit number of the sanding paper provides information about the number of abrasive particles on the abrasive.
Gypsum plaster surfaces have a lower degree of hardness than, for example, lime cement plaster walls. You must be careful when sanding down gypsum plaster. A grain size of at least 220 is recommended. Treating the gypsum plaster too roughly with a small grain size will not only grind protruding particles from the surface. The wrong abrasive can cause deep grooves and dents in the plaster.

  • Also read - sanding gypsum plaster
  • Also read - gypsum plaster for the basement
  • Also read - gypsum plaster or lime cement plaster for indoor use

Brief overview of grain sizes

  • Grit 6 to 30: Coarse abrasive
  • Grit 36 to 80: Medium abrasive
  • Grit 100 to 180: Fine abrasive
  • Grit 220 to 1000: Very fine abrasive

Abrasive grains can consist of different materials. Grains made from aluminum oxide and silicon carbide are particularly common. Both have a high degree of hardness. Alumina abrasive grains are tougher than silicon carbide grains and wear more slowly.

Different grits for the sanding mesh

For manual sanding, first use a hand sander with a sanding mesh. In the first step, the grain size may be a little smaller. The sanding screen is moved evenly over the gypsum plaster in circular movements. It must lie directly on the surface, but it must not be moved with too much pressure. The grille is incorrectly positioned if it causes welts in the plaster or even tilts. If lumps form on the sanding screen, stop working immediately. In this case, the gypsum plaster is not yet completely dry. For the fine work, use a high-grain sanding screen.

Tips & Tricks Depending on the desired wall design, a sanding screen with a grain of 100 is sufficient. This surface is perfect for tiles and wallpaper. Finer-grain abrasives must be used if the surface is to be smoothed and painted.