Sandpaper: How to find the right grit
For a clean, precise, and easy finish when smoothing or polishing, nothing beats sandpaper. But which sandpaper is right for which job, and how do you find the correct grit? Find all the tips you need in our big sandpaper guide!
What is sandpaper?
Sandpaper is a piece of paper coated on one side with small, irregularly shaped abrasive grains. These grains scratch the surface of the workpiece during sanding, removing material. Depending on the size of the grains, the sandpaper will provide a coarse or fine removal of material with each pass.
Since it was first invented, sandpaper has been made of 4 layers:
- Backing material: a robust, tear-resistant material like paper (for DIY projects and trades) or fabric and vulcanised fibre (for industrial use).
- Base coat: a layer of glue or synthetic resin that holds the backing and abrasive grains together.
- Abrasive grains: the actual “tool”, made from aluminium oxide (corundum), silicon carbide or diamond.
- Top coat: a final layer of synthetic resin or glue to prevent the grains from wearing away. It is often coloured to help identify the sandpaper grit.
Did you know?
Sandpaper is also known as emery paper, because the abrasive particles were originally made from natural sand or emery.
What is sandpaper used for?
Sandpaper is an essential accessory for many detailed jobs and DIY projects. You can use it for tasks such as:
- Sanding wood
- Polishing metal
- Rounding off edges
- Deburring workpieces (removing sharp edges)
- Smoothing plaster
This makes sandpaper just as indispensable for upcycling furniture as it is for renovating a wall or removing rust.
Depending on the task, you can use sandpaper either by hand or with a sander. As a rule of thumb: the more delicate and smaller the workpiece, the better it is to sand by hand. For large surfaces, it's best to use a power tool.
The right sandpaper grit – chart & tips
The key to choosing sandpaper is getting the grit right. This refers to the size of the abrasive particles, which determines how fine the finish will be. The rule is: the higher the grit number, the finer the sanding; the lower the grit number, the coarser the sanding.
Sandpaper grit is standardised according to FEPA (Federation of European Producers of Abrasives). It always starts with a "P" followed by a number:
- P12 to P30: coarse
- P30 to P80: medium-coarse
- P80 to P180: fine
- over P180: very fine
When sanding, you should always work your way from a coarse to a fine finish, which means using several different sandpaper grits. For typical jobs, the recommendations are as follows:
Aufgabe | Empfohlene Körnung |
|---|---|
Wand schleifen per Hand (aus Stein oder Rigips) | P60 bis P80 |
Abschleifen von Parkettkleber oder Estrich | P24 bis P30 |
Alte Farbe oder Lack von Holz entfernen | P80 bis P240 |
Holz anschleifen vor Lackieren | P180 |
Holz glätten | P80 bis P280 |
Kratzer im Autolack entfernen | P3000 bis P5000 |
Metall polieren | P150 und feiner |
Metall entgraten | P60 und feiner |
INFO:
Understanding grit coating
The grit coating indicates how densely the abrasive grains are packed onto the sandpaper. There are three categories:
- Open coat: 50 to 70% of the surface
- Semi-open coat: 70 to 80% of the surface
- Closed coat: almost 100% of the surface
The more open the coat, the less material is removed. An open coat is therefore ideal for materials that tend to clog the sandpaper, such as resinous softwoods or soft layers of varnish. In contrast, you should use a closed coat for hard materials like ferrous metals, as very little material gets stuck between the grains. A semi-open coat is the all-rounder for hardwood, plastic and non-ferrous metals.
Sandpaper: Questions & Answers
You should change the sandpaper when you notice less dust is being removed during sanding, or if the sanding surface feels smooth.
Some sanders feature a built-in dust extraction system to collect dust produced during sanding. This works via the pre-punched holes found on certain types of sandpaper.
Extra-fine sandpaper is used to remove scratches from car paintwork, ensuring minimal material is removed.
For wet sanding, sandpaper with a full synthetic resin bond is ideal. Vulcanised fibre and fabric backing also improve the sandpaper's durability when used wet.
Specially shaped sanding belts for belt sanders, designed not to tear during use.
