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? You’ll find all the tips in our comprehensive sandpaper guide!
What is sandpaper?
Sandpaper is a sheet of paper coated on one side with small, irregularly shaped abrasive grains. These "grits" scratch the surface of the workpiece during sanding, removing material. Depending on the size of the grains, sandpaper provides either a 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 off. It is coloured differently 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Sandpaper is also known as emery paper because the abrasive particles were originally made from natural sand or emery.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 to:
- Sand wood
- Polish metal
- Round off edges
- Deburr workpieces (remove sharp edges)
- Smooth 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 both by hand and with sanding machines. As a rule of thumb: the more delicate and smaller the workpiece, the better it is to work by hand. For large surfaces, it's best to use a power tool.
The right sandpaper grit – Guide & Tips
The key to choosing sandpaper is the right grit. This describes the size of the abrasive particles and the fineness of the finish. Remember: the higher the grit number, the finer the finish; the lower the grit number, the coarser the finish.
Sandpaper grit is standardised according to FEPA (Federation of European Producers of Abrasives). It always starts with a "P" and a corresponding 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, meaning you will use several types of sandpaper. 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:
A guide to sandpaper coating
The coating of the abrasive grains indicates how densely the grains are packed on 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: approximately 100% of the surface
The more open the coating, the lower the material removal. An open coat is therefore ideal for materials that tend to clog, such as resinous softwoods or soft layers of lacquer. On the other hand, you should use a closed coat for hard materials like ferrous metals, as hardly any material gets stuck between the grains. A semi-open coat is the all-rounder for hardwood, plastic and non-ferrous metals.
Sandpaper: Questions & Answers
Sandpaper should be replaced when it is noticeably removing less dust, or if the sanding surface feels smooth.
Some sanders feature an integrated dust extraction system for the dust produced during sanding. This works via holes which are punched into certain types of sandpaper.
For removing scratches from car paint, extremely fine sandpaper is used to remove as little material as possible.
For wet sanding, use sandpaper with a full synthetic resin bond. Vulcanised fibre and fabric backing also increase the durability of the sandpaper for wet use.
Specially shaped sanding belts are available for belt sanders, designed to be tear-resistant during sanding.
