Home & leisure
Sanders
Introduction
You've got paint to strip, wood to smooth, a window frame to clean up ... what type of sander will do the trick?
We explain the difference between the bewildering array of sanders you may be faced with at the hardware store: disc, orbital, detail and belt sanders. We also tell you what jobs they're most suited to.
Note: this report does not contain test results or brand-specific information.
Disc and orbital sanders
Disc sander
The original electric sander is likely to have been sandpaper attached to a disc fitted to end of a power drill. If you've got a drill, this is still the simplest and cheapest option. Rotary sanding discs can remove a lot of material in not much time.
Unfortunately, it's easy to leave swirl marks and gouges that are difficult to remove. Getting a good finish with a disc sander takes a bit of practice. They're more suitable for smoothing rough timber or removing old paint.
Orbital sander
These sanders use an oblong rubber pad with sandpaper attached, that moves very fast in a circular motion just a few millimetres in diameter. This movement is difficult to see, but you can feel the vibration in the handle of the machine.
Orbital sanders are designed for fine surface finishing, not for the removal of large amounts of material. They are easy to use, although you need to keep the pad moving at all times or tiny swirl marks can appear.
The pad is oblong so you can get into corners.
Detail sander
A variation on the orbital sander with a triangular-shaped sole. This allows you to reach awkward places like around window frames.
The forward-facing tip gets most wear, so the sole can be adjusted to set each tip to the front. Some versions have a sole shaped rather like a clothes iron.
Random-orbital sander
A combination of disc and orbital. The round disc moves in tiny circles, like an orbital, but is also free to rotate. The net effect is that the machine removes material faster than an orbital, and doesn't leave score marks like a disc, or swirl marks like an orbital.
Random-orbital machines - especially models with adjustable dual orbits - provide the best combination of rapid material removal, ease of use and good finish. But the round pad cannot get into corners.
Belt sanders and hand sanding
Belt sander
These machines have a loop or belt of abrasive cloth that is tensioned between rotating front and rear drums. They're designed for rapidly smoothing timber and removing old paint, but they can be tricky to use. You need to keep them moving at all times, and never run them across the grain of the timber, or they will produce very deep score marks.
Sanding by hand
You don't always need a machine, of course. For getting into tight spots, or flatting gloss paint and light finishing, a folded sheet of sandpaper and a bit of elbow grease could be all that's required.
If you're doing larger surfaces like walls and tabletops, wrap the sandpaper over a block of wood (you can buy them faced with cork, which softens the abrasion and therefore helps avoid scratching). This will produce faster, more consistent results.
For reaching up walls, you can get sanding blocks that attach to a broomstick via a pivoting joint.
What sander for what task?
We explain what types of electric sanders are suitable for certain tasks.
Choosing the right paper
You need to get the right paper for the job at hand ...
Open-coat abrasives
Special open-coat papers are available for dry-sanding painted surfaces. Open-coat papers don't clog up as quickly - especially when sanding soft acrylic paints, and can be identified by the grey/white coating colour.
Grit size and type
Generally, the softer the surface you want to sand, and the more material you want to remove, the bigger the grit size should be.
But bigger grit sizes leave deeper scratch marks. The solution: finish off using the "double and back one" rule. This means if you do the bulk of the job with, say, 60 grit, you should finish off with a paper that is 60 x 2 = 120, back one grit size = 100 grit.
Grit size is commonly printed on the back of the paper - the higher the number, the smaller the particle (240 grit is finer than 100 grit).
Alternatives to sanding
Paint removal doesn't have to be done with a sander. Some alternatives:
Mesh grit wheel
This is a grit-impregnated coarse nylon wheel or disc that you attach to a drill or small angle grinder. It won't clog up like paper, and can be very useful for rapidly stripping paint from metal and other surfaces, especially on irregular shapes.
Not so good for large flat surfaces, such as walls.
Scraping
Possibly the best way to remove paint from around window and doorframes. Tungsten carbide scrapers last well and are available in different shapes.
Chemical stripping
For removing hardened old paint, the combination of chemical stripper and a scraper can be pretty quick. But remember - paint stripper is extremely toxic. Don't use it inside unless you can ensure very good ventilation.
Sugar soap
A useful alternative to sanding prior to repainting, especially if all you're doing is removing grease from an old gloss finish. Good for large surfaces, when the existing paint film is sound.
Hot-air gun
The heat softens the old paint film to allow much easier scraping. A burner or blowtorch will also do the job, but they're dangerous. Hot-air guns have no flame, so scorching is reduced - you're much less likely to burn the house down.
Paint-removal machine
A depth-controlled set of carbide blades rotates at high speed to scrape away the paint. These machines can be so finely set that individual layers of paint can be removed. Ideal for weatherboards and other flat surfaces. They cost close to $1000 to buy, but they're also available for hire.Our advice
When you buy
Ask in the shop
If you're buying a sander for the first time or you're not sure if you've made the right choice, ask the shop attendants to show off their knowledge. They should be happy to oblige. If it's obvious they don't really know what they're talking about, go some place where they do.
Check the warranty
Power tool makers produce different ranges for different market segments, ranging from home/DIY through to industrial/commercial. If you can afford a tool with a trade-use warranty, it's likely to be higher quality than one limited to home use.
But amongst the DIY tools, warranties vary widely. Some manufacturers offer only one year, while others offer two or four. A long warranty is an attractive bonus if the machine is suitable for your tasks.
Choose mains power
Battery-powered sanders are available, but we're sceptical. Sanders get used for extended periods of time, which means the battery can run down quickly. It's not like using a drill, where the short bursts required to drive in screws or drill let you get through lots of work. For most jobs, mains-powered sanders are better.
When you use your sander
- Choose the right sander with the right abrasive for the job at hand.
- Don't push hard. Let the machine do the work and keep moving at all times.
- Every couple of minutes, lift the sander off the work to inspect your progress. Blow the sanding dust away, to see how you're going and to prolong the paper life.
- Replace the abrasive when the sanding performance tapers off.
- Wear safety glasses or goggles, ear protectors and a dust mask.
- If you want to sand lead-based paints, you need full protective clothing, including overalls and a suitably rated dust mask.
More help
DIY building: www.buildeazy.com
Lead paint: ACC guide