Whether they’re sanding decks, ripping down hardwood boards, removing layers of paint or finishing interior woodwork, builders rely on abrasives to finish, repair and restore. But working with abrasives can be more art than science. Each job requires a different type of abrasive and a different type of approach involving a range of tools from orbital sanding disks to block sanders to angle grinders.
How do you know which abrasive and which tool to choose? Here’s a look at four of the most common questions building professionals have when choosing abrasives — and expert answers to help get the job done right:
1. How can I prevent discs from loading when stripping old coatings? You can’t always prevent this problem from happening, but there are a few ways to minimize loading and get more life from your abrasives. First, don’t try to strip off coatings with too fine of a grit. The finest grit you should use when stripping coatings is 80 grit. If you’ve started with an 80-grit disc and notice it is loading quickly, you will probably need to drop down to a 60- or 40-grit disc. Also, keep in mind that the sanding process generates heat, which softens old coatings and causes them to load. Using too much sanding pressure and moving the sander slowly will cause excessive heat. Try lightening up on the pressure and move the sanding over the work piece more quickly, this will help reduce loading. ProSand discs are stearated, which helps minimize loading.
2. Why would I use a ceramic abrasive over a traditional aluminum oxide? Ceramic grain, which is used in ProSand discs, has several advantages over aluminum oxide. Ceramic grain is sharper and lasts longer than aluminum oxide. This difference allows you to sand faster and sometimes start a grit finer than you normally would with a standard abrasive disc. Ceramic grains are also very uniform in shape and size, so they leave a very fine scratch pattern, finer and more consistent than an aluminum oxide disc. Because ceramic grain is sharper and lasts longer it makes ceramic the ideal choice for sanding hardwoods like oak and maple.
3. I hear that ceramic sanding discs cut more aggressively than aluminum oxide. Does this mean I need to sand to a finer grit than I normally would, and that I can’t use them on soft woods? Ceramic grain is sharper than aluminum oxide so when sanding it can feel like the disc is more aggressive. But because of the shape of the ceramic grain, it actually leaves a finer scratch pattern than aluminum oxide discs. So, you don’t need to finish with a finer grit. Ceramic discs can be used on all woods, from softest to hardest. You will probably be able to start a grit or two finer than you normally do with standard discs when sanding softer woods.
4. What grit should I use to strip an old coating? The rule of thumb is, don’t start sanding any coarser than you need to. If you don’t put coarse sanding marks into the wood, you won’t need to spend extra time to get them out. 80 grit is a good place to start if you need to sand off light coatings that don’t load. If sanding thicker paint or varnish, start with 60 grit, and if needed go down to 40 grit.
For assistance with your projects, reach out to the Norton Abrasives team.
