Sandpaper: How to find the right grit
For a clean, precise, and easy finish when smoothing or polishing, nothing beats sandpaper. Which sandpaper is suitable for which job and how do you find the right grit? Find all the tips in our big sandpaper guide!
What is sandpaper?
Sandpaper is a sheet of paper coated on one side with small, irregularly shaped abrasive grains. These grains scratch the surface of the workpiece, removing material as you sand. Depending on the size of the grains, the sandpaper allows for coarse or fine removal with each pass.
Since its invention, sandpaper has been made of 4 layers:
- Backing material: a robust, tear-resistant material like paper (for DIY projects and crafts) 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 of 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Sandpaper gets its name because the abrasive particles were originally made from natural sand or emery.
What can you use sandpaper for?
Sandpaper is an essential accessory for many finishing touches 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 a must-have for upcycling furniture, renovating a wall or removing rust.
Depending on the task, you can use sandpaper either by hand or with a sanding machine. 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.
Choosing the right sandpaper grit – Chart & tips
The key to choosing sandpaper is getting the right grit. This describes the size of the abrasive particles and how fine the finish will be. The rule is: the higher the grit number, the finer the sand; the lower the grit number, the coarser the sand.
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 grit, which means using several different grades of sandpaper. Here are the recommendations for typical jobs:
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 refers to how densely the abrasive grains are packed onto the sandpaper. There are three main categories:
- Open coat: 50% to 70% of the surface is covered
- Semi-open coat: 70% to 80% of the surface is covered
- Closed coat: Almost 100% of the surface is covered
The more open the coat, the less material is removed. An open coat is therefore ideal for materials that tend to clog the paper, such as resinous softwoods or soft layers of paint. 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 FAQs
You should change the sandpaper when you notice it's removing less dust, or if the sanding surface feels smooth.
Some sanders have a built-in dust extraction feature to collect sanding dust. This works via the pre-punched holes found on certain types of sandpaper.
When removing scratches from car paintwork, extremely fine sandpaper is used to remove as little material as possible.
Sandpaper with a full synthetic resin bond is ideal for wet sanding. Vulcanised fibre and fabric backing also increase the sandpaper's durability for wet use.
Specially shaped for belt sanders, these sanding belts are designed not to tear during use.
