Choosing the right abrasives saves time and money
When you first became a painter, you probably didn’t realize how much time you would spend sanding. However, you quickly discovered that it’s a critical component to getting a beautiful final product.
Maximizing productivity, efficiency, and performance on the job site begins with choosing the right sandpaper and abrasives.
“Time is money,” says Dwight Schoenherr, advanced specialist application engineer at 3M. “The less time I spend sanding and finishing, the more jobs I can get to. That’s what the right abrasives can bring to the pro who’s asking, ‘How can I get this job done more quickly and still have a great-looking finished product?’”
From new efficiency-enhancing technology to advice on getting more out of your gear, 3M’s experts shared five ways for painting contractors to improve their knowledge of abrasives.
1. Start with the substrate
When choosing the right abrasive, consider the surface you’ll be sanding.
“When it comes to sandpaper, a lot of people think, ‘I just need to grab a sheet and it’ll work fine with whatever I’m working on,’” says 3M’s Dave Gomis. “But that’s not always the case. Factors like the application method, the goal, and the substrate in question all matter.”
Each substrate requires a different approach. When sanding unpainted or primed drywall, you’ll want to use a fine or very fine grit, like 220 or 320 grit, to get a soft, smooth finish with as few scratches as possible. To sand wood, you’ll likely want to use something coarser, like 150 or 180 grit, but not too strong. On the other end of the spectrum, removing coatings from previously painted surfaces—such as a window or a door—may require a very coarse grit like 60 or 80.
Beyond the grit, the product type you select should be based on the shape and layout of the substrate. Contractors working on curved or textured surfaces will likely find sanding sponges to be most comfortable and efficient, while those working on a flat surface—typically with a power tool such as a random orbital sander—will find sandpaper discs and sheets more helpful.
2. Match the grit to the job
Sandpaper will be labeled with a grit number, which reflects its level of coarseness. The higher the number, the finer the sandpaper. Extra coarse abrasives (60 to 80 grit) are great for removing old paint and varnish layers, while extra fine (400 grit) help ensure a smooth finish on new coatings. Many jobs will begin with coarser abrasives and gradually use finer types to get a smooth finish, though this will vary based on your goal.
For those looking to remove old layers, Sherwin-Williams recommends 60 and 80 Coarse discs and sheets.
To smooth out existing layers or surfaces, try Medium-grade products. 100 and 120 grit Medium are recommended for sheets and discs, as are 100 grit Medium sponges.
And to get a smooth, professional fine surface, use Fine or X-Fine graded products. Sponges from 120 to 220 grit, sheets from 180 to 400 grit, and discs at 220 grit will all work well for this.
3. Consider new grit technologies
Due to innovations in abrasives over the last couple decades, grit is no longer a universal standard for coarseness. Some product lines, such as 3M’s purple Pro Grade Precision line, sand much more efficiently than their grit number would suggest.
“Nowadays, with the technology we’re putting in our abrasives, if you’re using the traditional 100-grit core line, and then you use the 100-grit Pro Grade Precision that’s on the shelf at Sherwin-Williams, it’s a day and night difference,” Schoenherr says. “It’s to the point that you might actually have to go up to a finer grit, like 120 or maybe even 150, to get a comparable cut to what you’re familiar with.”
The secret to the Pro Grade Precision’s increased efficiency is a triangle-shaped ceramic mineral that has been added to the mineral blend which coats 3M’s abrasives. What makes these ceramic minerals more abrasive than traditional sandpaper?
“I like to relate it to glass,” Schoenherr says. “No matter how small I break a piece of glass, I can always cut myself on it, right? That’s what this is doing.
“Instead of traditional minerals that plow into the substrate you’re trying to sand, we cut right through it. Now you have a cutting surface that will cut through whatever you’re sanding far more efficiently than anything else on the market.”
The Pro Grade Precision line also features No-Slip Grip backing which helps eliminate the finger and hand fatigue often caused by pinch-gripping sandpaper.
Whether your preference is the familiar core line or the premium Pro Grade Precision line, it’s important to check the packaging and choose the product that meets your project’s needs.
4. Don’t give up on your abrasives too early
Schoenherr cautions painters not to throw out their sandpaper when it first gets “loaded,” or so gummed up with residue that it appears worn out or no longer useable. He says loading can be easily fixed by cleaning the abrasive.
“All of our premium abrasive sheets and all sponges can be rinsed and reused,” Schoenherr says. “If my sandpaper is fully loaded, I can just put it in a bucket of water and rinse it. As long as what I’m sanding isn’t affected by water, you can then continue to use it. If the substrate is affected by water, then set it aside and you can use it once it’s dry. You’d be surprised how much life is still left in it.”
That especially applies to 3M’s Pro Grade Precision abrasives. In addition to enhanced efficiency, these premium abrasives last about ten times longer than traditional abrasive products. They’re also embedded with a special cleaning compound called “stearate” that helps contractors clear off the loading easier.
5. When in doubt, ask an expert
With so many options to consider, some contractors may need help trying to choose the right abrasive. If so, ask your local Sherwin-Williams sales representative what products they recommend based on the job specs you’re looking at. They can point you in the right direction and can suggest specialty products that fit your needs.