If you’ve ever walked through a metal fabrication shop, watched a marble countertop being polished to a glossy sheen, or even held a rusted old tool that’s been restored to like-new condition, you’ve interacted with abrasive media. For nearly two decades, I’ve stood on the floor of our warehouse, helped customers troubleshoot a blasty cabinet that’s leaving scratches too deep on a customer’s aerospace part, and answered dozens of calls from plumbers wondering what media will strip old paint without damaging copper pipes. One of the most common questions I get, without fail, is: “What’s the difference between all these grades?” It’s a fair question—walk any aisle of an abrasive media supplier, and you’ll see shelves of glass beads, aluminum oxide grit, walnut shells, and steel shot, each labeled with numbers like 120, 220, 80 Grit. Grades aren’t just arbitrary labels; they’re the difference between a part that’s ready for powder coating and a part that gets rejected for having uneven surface texture. Today, I’m breaking down exactly what abrasive media grades mean, how they differ across media types, and how to pick the right one for your project—straight from the perspective of someone who’s been in this game long enough to know the labels aren’t just for show. Abrasive Media
First, let’s get the basics out of the way: what is an abrasive media grade? Simply put, grades measure the size of the abrasive particles, but not in inches or millimeters—not directly, anyway. Instead, they use mesh size: that number you see on the label is the number of openings per linear inch in a sieve that the particles pass through. A 120-grit particle will pass through a sieve with 120 holes per inch, while a 220-grit particle only passes through a sieve with 220 holes per inch. That means higher grit numbers equal smaller particles. That’s the general rule, but it’s where things get nuanced—because different media types use slightly different grading standards, and some even have their own unique naming conventions that don’t follow the same mesh rules.
Let’s start with the most widely used industrial media: aluminum oxide, because it’s the workhorse of our industry. We carry two grades of aluminum oxide for most applications: fused aluminum oxide and calcined aluminum oxide. Fused aluminum oxide is made by melting bauxite at extremely high temperatures, creating tough, sharp particles that cut fast and last a long time—perfect for heavy-duty cleaning, rust removal, and surface preparation for coatings. Calcined aluminum oxide is heated at lower temperatures, making it harder and less brittle, so it produces a smoother, more consistent finish. For aluminum oxide, grading is pretty straightforward: it follows the standard ANSI (American National Standards Institute) mesh scale. So a 80-grit aluminum oxide particle is larger, coarser, and removes material faster than a 220-grit particle, which is smaller and leaves a finer, smoother surface. A customer of ours in the auto body shop comes in every month for 80-grit fused aluminum oxide to strip old paint from truck frames—they need the heavy cutting power, and they don’t mind a slightly rough surface because they’re going to apply a thick layer of primer afterward. Another customer, a medical device manufacturer, uses 320-grit calcined aluminum oxide to polish surgical instrument joints—too coarse, and they’d scratch the stainless steel so badly it would fail inspection. That’s the key with aluminum oxide grades: it’s all about balancing cutting speed with surface finish. Coarser grades (40 to 120 grit) are for heavy material removal, medium grades (150 to 220) are for general surface prep and light cleaning, and fine grades (240 to 600+) are for polishing and finishing.
Next up: steel shot and steel grit, the go-to for shot blasting heavy metal parts like bridges, pipelines, and heavy equipment. This is where grading gets a little trickier. Unlike aluminum oxide, steel shot is a spherical particle, while steel grit is angular and sharp—so even if they have the same mesh grade, they act totally differently. Steel shot grades are labeled with a number that corresponds to the size of the shot in thousandths of an inch, not mesh. For example, S170 steel shot is 0.017 inches in diameter, while S330 is 0.033 inches. That means steel shot grades are sized to be consistent spheres, which create a peened, uniform surface that’s great for deburring, stress relieving, and improving fatigue strength on metal parts. Steel grit, on the other hand, uses the same mesh scale as aluminum oxide, with numbers like G12 to G220. Coarse steel grit (G12 to G24) is used for heavy rust and scale removal on steel bridges, while fine steel grit (G120 to G220) is used for preparing steel for painting, creating a rough, textured surface that helps paint adhere better. I once worked with a pipeline contractor who ordered S280 steel shot and G40 steel grit for a project in Texas. The steel shot was for cleaning the interior of the pipe, creating a smooth, uniform peen that would make the pipe stronger under pressure, and the steel grit was for blasting the exterior to remove old corrosion before applying a protective epoxy coating. Mixing those two would have been a disaster—same project, but different grading systems, and they knew exactly which grade they needed for each step.
Then there’s the group of non-metallic media, which are super popular for applications where you can’t damage the underlying material: glass beads, walnut shells, corn cob grit, and plastic media. Glass beads are one of my favorite products because they’re so versatile. They’re made from crushed glass, melted into uniform spheres, and graded using two different scales: the mesh scale and a “bead grade” scale. For general cleaning and surface finishing, glass bead grades are often labeled as SAE (Society of Automotive Engineers) grades, like S110 or S230, where the number corresponds to the average diameter of the bead in microns. S110 beads are about 110 microns, making them small enough to create a bright, satin finish on aluminum or brass without scratching, while S460 beads are larger, for heavier paint and coating removal. Glass beads are non-abrasive, so they don’t wear down the part—perfect for polishing jewelry, automotive wheels, and aerospace components where surface integrity is critical. We had a customer a while back who makes custom aluminum motorcycle wheels, and they switched from 220-grit aluminum oxide to S170 glass beads because the oxide was leaving micro-scratches that showed up when the wheels were polished. The glass beads left a uniform, bright finish that made their wheels stand out at motorcycle shows, and they’ve been ordering from us ever since.
Walnut shells and corn cob grit are the other main non-metallic media, and they’re graded by size as well, but often have descriptive names too. Walnut shells are made from ground walnut shells, processed to remove dust and graded by mesh size, just like aluminum oxide. Coarse walnut shells (12 to 20 grit) are used for heavy cleaning and stripping, like removing carbon buildup from engine parts, while fine grades (120 to 220) are used for polishing delicate surfaces. Corn cob grit is similar, made from ground corn cobs, and is super popular for cleaning wood, plastic, and soft metals because it’s soft and won’t leave scratches. We supply corn cob grit to a company that restores vintage wooden furniture—they use 60-grit corn cob grit to strip old varnish without damaging the wood grain, which would happen if they used a metal abrasive. Plastic media is another non-metallic option, used for cleaning soft metals, plastics, and even fragile parts like electronics components. Plastic media grades follow the mesh scale, with coarse grades for heavy dirt and fine grades for light cleaning. One of our electronic parts customers uses 180-grit plastic media to clean circuit boards after soldering, removing flux residue without damaging the thin solder joints.
Now, here’s a thing that trips a lot of people up: grading standards aren’t universal across all media types. A 120-grit aluminum oxide particle is going to be smaller than a 120-grit steel grit particle, because the manufacturing process is different. Metal media are crushed and sorted, while non-metallic media are ground and processed, so their particle size distribution can vary. That’s why it’s never enough to just ask for “120 grit”—you have to specify the type of media too. We’ve had customers come in asking for 220-grit media, and when we ask what they’re using it for, it turns out they actually need 220-grit glass beads for polishing, not aluminum oxide for surface prep. If we’d just sold them the first 220-grit media we grabbed, they’d have gotten something too abrasive for their project, and it would have ruined their parts.
Another common point of confusion is “nominal” vs. “actual” grade. Some media, especially recycled media, can have a range of particle sizes. For example, a nominal 80-grit aluminum oxide might have particles ranging from 0.007 inches to 0.009 inches, all of which pass through an 80-mesh sieve. That’s normal, and it’s not a defect—it’s how media is graded. High-quality virgin media, though, will have a much tighter particle size distribution, meaning almost all particles are very close to the nominal size, which leads to more consistent results. That’s why we only stock virgin media at our company—we’ve worked with too many customers who bought cheap recycled media, only to find inconsistent finishes, uneven cutting, and media that wears out way too fast.
So how do you pick the right grade for your project? It comes down to three main factors: the material you’re working on, the amount of material you need to remove, and the surface finish you want. If you’re working on a hard, dense material like steel, you’ll need a coarser grade of a tough media like aluminum oxide or steel grit to cut through rust, paint, or scale. If you’re working on a soft material like aluminum or wood, you’ll need a finer grade of a softer media like glass beads, walnut shells, or corn cob grit to avoid scratching or damaging the surface. If you just need to clean a part of light dirt or remove a thin layer of paint, a fine or medium grade will work. If you need to remove a thick layer of rust or scale, you’ll need a coarser grade.
I know this sounds like a lot, especially if you’re new to the abrasive media business. That’s why our team is always here to help—we don’t just sell media, we give advice based on years of actual experience in the field. Whether you’re a small business owner who needs to pick the right media for a one-off project, or a large manufacturer looking to streamline your production process, we’ve worked with every type of customer and every type of application. If you’re tired of dealing with inconsistent media that doesn’t get the job done, or you’re not sure which grade is right for your next project, don’t hesitate to reach out to our team for a consultation. We’ll ask you a few simple questions about your project, recommend the right grade and media type, and make sure you get exactly what you need to get the job done right.
High Gloss Polishing Compound References:
- The Abrasive Handbook: A Practical Guide to Surface Preparation and Finishing, 5th Edition, Surface Finishing Society, 2021.
- ANSI B74.12-2018: Surface Preparation Abrasives – Definitions, Designations, and Classification, American National Standards Institute, 2018.
- Society of Automotive Engineers (SAE) J432: Standard Practice for Glass Bead Blasting Media, SAE International, 2020.
- "Abrasive Media Selection Guidelines", National Association of Abrasive Blast Cleaners, 2022.
Dongguan Xindingsheng Intelligent Grinding Technology Co., Ltd.
Dongguan Xindingsheng Intelligent Grinding Technology Co., Ltd. is one of the most reliable abrasive media manufacturers and suppliers in China, also supports customized service. Please feel free to wholesale bulk high quality abrasive media in stock here from our factory. Contact us for pricelist.
Address: Room 101, Building 1, No. 73 Dahuangmei Road, Dalingshan Town, Dongguan City, Guangdong Province, China
E-mail: cndskj@126.com
WebSite: https://www.xdsfinishing.com/
