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Sanding down wood and metal: a guide to sanding

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You've probably already noticed from your previous DIY projects that sanding is often a very important part of the process. We've put together a guide that explains why sanding is useful, what differences there are between various types of sanding equipment such as sanding paper or sanding sponges, and how to choose the right one. We've also added a few tips that will help you decide which device is most suitable for your project.


1. Why is sanding down so important?

When you think of sanding, wood is probably the first material that comes to mind. Sanding down wood removes old paint or varnish and prepares the surface for painting or varnishing. By sanding down metal, you can remove rust and enhance the look of the metal in the process.

2. Which sanding technique should I use for my object?

The right sanding technique depends on the result you want to achieve. You should also consider what condition the material is in at the start of the project: is it an old cabinet that you want to do up, for example? Or do you just want to sand down the sawn-off edges of a piece of wood to remove splinters? There are a wide range of different sanding methods and grits of sanding paper you can use to get the desired result. Depending on the size of your object, you can decide whether you want to use a sanding machine or sand by hand.

2.1 Coarse sanding/removing material

When you want to remove a lot of material, this is known as coarse sanding. This is often the first step when doing up an item like an old cabinet, for instance. You should use coarse sandpaper (40 to 60 grit) for this kind of project. Course sanding removes old paint or varnish and enables you to sand down raw, rough surfaces.

2.2 Preparing the material

If you just want to sand away a little bit of material or prepare an item for the next stage of a DIY project, 80 to 120-grit sanding paper should be suitable. Using this type of sandpaper will even out any irregularities and get rid of any traces of coarse sanding.

To prepare the material for varnishing or painting, you should sand it down further using 80 to 120-grit sanding paper.

2.3 Fine sanding

Use fine sanding to get rid of any traces of earlier sanding and to make the material ultra smooth. With 180-grit sanding paper, you can remove fibres from the surface and prepare the material for staining or varnishing.

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Our tip

Sanding down between coats of paint delivers the best results. To do this, sand down the material again after applying the first coat, making sure the paint is completely dry before you start. It's best to use 240-grit sanding paper for this.

2.4 Polishing

For best results, you should polish your material after sanding it down. To do this, use a polishing felt or polishing sponge and run it over the finely sanded material.

3. What types of sanding equipment are there?

You can differentiate between different types of sanding equipment by looking at their grit and the base material. You should choose a suitable combination of sanding equipment according to what end result you're looking for.

3.1 What does a sanding paper's grit indicate?

Grit refers to how coarse or fine a piece of sanding paper is. Generally speaking, the higher the grit, the finer the sanding paper and the finer the end result will be. Grit tends to be divided into sizes that are 20 to 30 points apart, so the next size up from 60 grit would be around 80 grit, for example.

A coarse grit means the grain of the sanding paper is irregular and unevenly distributed. The end result will be less smooth but using a coarse grit enables you to remove more material when sanding. A finer grit means the sanding paper is more even, giving a cleaner result. This type of grit removes less material but doesn't leave any deep scratches in the material.

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Rule of thumb for grit

You should never switch to sanding paper that's more than one size higher than the one you've used previously. For example, if you use 80-grit sanding paper to begin with, you shouldn't switch to 180-grit sanding paper to give your material a smoother finish. It's better to switch to 120-grit sanding paper first before transitioning to a finer grit.

3.2 Various base layers of sanding equipment

3.2.1 Sanding paper/fabric

As the name suggests, paper is the most common base layer for sanding equipment and is available in coarse to fine grits. It's suitable for all types of sanding, from coarse to fine sanding. Some types of sanding paper are designed to be attached to sanding machines and come with holes which enable you to vacuum the sawdust as you go. Other types of sanding paper are available as sheets to use by hand or to wrap around a sanding block.

Some types of sanding equipment have a fabric base layer which is very durable and robust, making it less likely to tear during use.

3.2.2 Sanding sponge

If you need to work on something like a curved piece of wood, sanding equipment made of foam, such as sanding sponges, works very well on this type of surface. The pressure of your fingers is evenly distributed, ensuring that you don't leave any deep scratches on the surface of the material you're sanding. There is also no risk of sanding away too much. There are different grit sizes depending on what you are sanding, so if you're working on something that requires different grits, it's a good idea to get a sanding sponge set.

3.2.3 Liner

Liner is mostly used as the base layer for sanding equipment which is designed to be used by hand. It's ideal for using on wood before applying oil. Using liner enables you to remove the last small wood fibres and oil your wood at the same time.

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How should I store my sanding equipment

It's best to store sanding paper at room temperature, i.e. between 15 and 25 degrees Celsius, and at 40 to 60 per cent humidity. To ensure the best results and to make sure your sanding equipment lasts for longer, you shouldn't keep it on a concrete floor, or near open windows or heaters.

3.2.4 How do I choose the right sanding equipment for my project?

Step 1: Decide what material you want to sand down (e.g. wood) and what result you want to achieve, such as preparing it for painting or varnishing.

Step 2: Select the right sanding technique.

Step 3: Choose the right sanding equipment, such as 120-grit sanding paper.

3.2.5 What do I need to look out for when sanding down certain materials?

Generally speaking, it's important to protect yourself from sawdust. It's best to wear a face mask and safety goggles while sanding, and it's also a good idea to put on ear defenders and work gloves when using a sanding machine.

3.3 Remove rust from metal and prepare it for varnishing or painting

You can remove rust by sanding down metal, as well as preparing it for varnishing or painting at the same time. Make sure you wear protective clothing.

3.4 What's important to bear in mind when sanding down wood?

When you're working on wood using an orbital sander, a belt sander or a random orbit sander, you should pay attention to the grain of the wood and take care not to sand against the grain to avoid leaving unwanted marks.

4. Which equipment is most suitable for my object?

There are many different ways of sanding. To sand down your material, you can do it by hand using a sanding sponge or sanding block, or alternatively you can use a sanding machine. We show you which equipment is best suited for which purpose:

4.1 Sanding curved contours

To make sure you don't ruin the curved contours of your material when sanding, you should select the right sanding tool. A sanding roller or sanding sponge are ideal for this type of project. They are more flexible than machines (which have a fixed sanding plate) or a sanding block, meaning you can easily follow the contours as you sand. Our crown-shaped children's coat hanger DIY project is a good example of where you can use sanding sponges.

4.2 Sanding down large surfaces

Do you want to work on flat wood or composite wood surfaces and varnished or painted surfaces? Then an orbital sander is the best option to go for. Its sanding plates are rectangular, which means it works well on flat surfaces.

A large wooden board is sanded down using an orbital sander.
An orbital sander makes easy work of sanding large areas.

4.3 Sanding down corners, edges and small areas

Does the item you're sanding have a lot of corners and edges and a small surface area, like in our plant hanger project? Then it's best to use a multi-sander for simple sanding. You can use different-shaped sanding equipment depending on what you need to do.

A multi-sander is used to sand down the edges of a wooden frame.
A multi-sander is useful for sanding corners

4.4 Sanding down the corners of small, intricate objects

If you want to sand small, intricate areas or objects by hand, you can use a delta sander. The triangular shape of the sanding plate is particularly well suited for smaller corners and precise sanding.

The corner of a door is sanded down using a delta sander.
You can easily sand down small areas using a delta sander

4.5 Sanding down large pieces of wood

Do you want to remove as much material as possible from your item? Then we recommend using a belt sander. To prevent any pitting occurring during sanding, you can attach a sanding frame to your belt sander to limit the sanding depth.

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Our tip

To avoid grooves and peeling while sanding, you should always place the machine you're using on the surface of the material before turning it on.

4.6 Quick coarse sanding – metal

If you simply want to remove as much material from a metal item as quickly possible rather than doing intricate work, it's best to use an angle grinder. With the right attachments, you can also use it on other materials such as wood.

A metal frame is sanded down using an angle grinder.
Use an angle grinder to remove a lot of material quickly

4.7 For objects of almost any shape

A random orbit sander can be used on almost any kind of material, regardless of its shape. Its round sanding plate enables you to make quick progress. The technique you use is similar to the way you would use an orbital sander: place the machine on the surface you want to sand, turn it on and guide it over the material.

A round wooden chest is sanded down using a random orbit sander.
Random orbit sanders are ideal for coarse and fine sanding on both round contours and flat surfaces

4.8 For sanding objects with shifting surfaces and different materials

To avoid having to constantly switch between different devices when sanding an item made of various materials, you can use a sanding roller. This is equipped with a flexible sanding wheel which is ideal for using on different materials. You can easily switch between the various attachments depending on the material you're working on without having to reach for an extra tool.

It's worth noting that the random orbit sander and delta sander are suitable for most DIY projects. But other sanding devices are recommended for more specific applications.

A sanding roller is used on different materials.
You can work on different materials using a sanding roller

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