Best sanding discs for random orbital sanders: picks by hole pattern, grain and backing

01What should a sanding disc for a random orbital sander have?

A disc for a random orbital sander should match the pad's size, use the same attachment system, line its dust holes up with the pad, and carry a grain and coating suited to the material. Fit comes first, because a disc that does not match the pad stops the extraction working.

Diameter: inch and metric names for the same discs

The two common sizes are 5 in, sold in Europe as 125 mm, and the larger size sold in Europe as 150 mm. All five picks on this page are the smaller size, the pad size of several models in the table below.

Attachment: hook-and-loop or PSA

Hook-and-loop discs can be removed and refitted several times, which suits stepping through grits, while pressure-sensitive adhesive (PSA) discs are usually thrown away once removed. PSA is usually the cheaper system, and its stiffer bond is preferred for levelling flat surfaces without rounding edges. Neither is better in every case, which corrects a common belief that PSA always wins. Our guide to hook-and-loop versus PSA discs covers the patterns in detail.

Hole pattern: line up with the pad

The common pattern on the smaller size has 8 dust holes. On the larger size, patterns of 6, 8 and more holes exist, and Festool uses its own 48-hole pattern. Holes only work when they line up with the pad's ports, and with extraction the abrasive lasts considerably longer. That corrects another misconception, that dust holes are decorative and any pattern will do. Mesh discs avoid the problem by drawing dust through the whole face.

Grain and coating: aluminum oxide or ceramic

Aluminum oxide is the general-purpose grain for bare wood and most metals; its blocky grains leave a fine, even scratch, which suits low-pressure orbital discs. Ceramic aluminum oxide is micro-crystalline and keeps exposing new sharp edges as it breaks down, and it was developed for aggressive stock removal on metal. Open-coat discs leave space between grains so dust can clear, which prevents early clogging on wood. A primer on aluminium oxide, zirconia and ceramic abrasives explains each grain against grit choice.

02What rules a sanding disc out before you compare grit?

A disc is ruled out if it is the wrong diameter, the wrong attachment or a hole pattern that blocks your sander's extraction. Those checks are quick, and the sander specs below show what common models use.

• Diameter. Read the pad size from the sander's manual or the table below. A 150 mm pad needs the larger disc; the picks here will not cover it.
• Attachment. Hook-and-loop discs need a hook-faced pad. A PSA pad has a smooth face and takes only adhesive discs.
• Holes. Most sanders of the smaller size take the 8-hole pattern. Festool sanders with their own multi-hole pads are one exception; Festool lists its MULTI-JETSTREAM 2 discs for its ETS, RO and LEX sanders.

Grit labels need one more check. CAMI is the US scale and uses plain numbers, while FEPA grades carry a P prefix. The two match closely up to about 220 grit, and in the range used on bare wood, FEPA papers are slightly coarser than CAMI papers of the same number. Mirka grades its discs on the P scale; Diablo and Bosch list plain numbers without stating the scale. The sandpaper grit chart lines the two systems up.

04How do mesh discs compare with punched-hole discs?

Mesh discs extract dust through their whole face and fit any hole pattern, while punched-hole discs extract only through holes that must line up with the pad. That is the main split among the picks, ahead of grain and grit.

Mirka Abranet vs Diablo SandNET: which mesh system?

Mirka Abranet is a net abrasive with aluminum oxide grain on a polyamide net and a hook-and-loop grip backing, so it goes straight onto any hook-and-loop pad. Diablo's SandNET uses a ceramic blend and comes with its own connection pad, and Diablo says the discs can be shaken, vacuumed or rinsed clean and reused. A widespread belief holds that mesh discs ruin hook-and-loop pads; the sources behind this page say Abranet uses a standard loop backing, and that pad damage comes more often from heavy pressure or debris on the hooks. Mirka still advises a pad saver for continuous sanding.

Diablo DCD050100H50G vs Bosch SR5R120: multi-hole or standard pattern?

Diablo's disc has a 12-hole universal (fits 5- and 8-hole sanders), so it suits mixed sanders in one workshop. Bosch's has the standard 8-hole pattern and an open-coat aluminum oxide grain, which Bosch lists for wood, veneer and paint. Diablo's ceramic blend is aimed at moderate stock removal and paint preparation in wood, metal and plastic. The choice comes down to whether all your sanders share the standard pattern and whether the work is mostly removal or mostly finishing.

Does ceramic beat aluminum oxide on an orbital sander?

Not automatically. Ceramic was developed for aggressive stock removal on metal, and it keeps exposing new sharp edges as it breaks down. Klingspor makes the same point about zirconia: it needs machine pressure to self-sharpen and glazes with too little. An orbital sander runs at light pressure, and aluminum oxide's fine, even scratch is described as suiting exactly that. The sources do not compare the two grains on orbital sanders directly, so treat ceramic as a removal grade and aluminum oxide as the finishing default.

05How do you get an even finish with these discs?

An even finish comes from light pressure, a slow pass, a clean surface between grits and a sensible grit sequence. The sander and the disc do the cutting; pressing harder works against both.

• Pressure. Use about 2–4 lb, roughly the weight of your arm. Pushing harder slows the pad's rotation and causes swirls. DeWalt's DeWalt DWE6423 manual makes the same point from the tool side: pressing down slows stock removal and leaves a worse surface, so let the sander do the work.
• Speed dial. On variable-speed sanders, DeWalt and Makita both advise higher speeds on harder materials and lower speeds on softer woods, veneer and plastics. A fine disc on veneer is a case for turning the dial down, not up.
• Travel speed. Move the sander slowly, about 1 in per second.
• Clean between grits. Vacuum or wipe the surface so loose coarse grit is not dragged around under the finer disc.
• Grit sequence. Woodcraft gives a standard wood sequence of 60, 80, 100, 120, 150, 180, 220 grit, working through each step. Stop at about 180–220 grit before staining, because finer sanding closes the pores and stain soaks in less evenly.

If the surface still shows loops after finishing, our guide to sander swirl marks lists the causes, from pressure to a worn pad.

06Does the sander's orbit change which disc you should buy?

It changes the grit you finish with more than the disc you fit. Disc fit is set by pad size, holes and attachment, but the orbit decides how aggressive a given grit feels. Festool sells the ETS EC 150 in two versions, and its manual lists strokes of 3.0 / 5.0 mm for the /3 and /5 models; both take the same 150 mm discs.

The practical reading is that a large-stroke sander suits the coarse removal grits, such as Diablo's ceramic-blend 100 disc, while a small-stroke sander is the better carrier for fine mesh or open-coat finishing discs. If you own only one sander, the speed dial and a full grit sequence do most of that work instead. Orbit and speed figures for other makers' sanders are tabled in the guide to which discs fit your orbital sander.

07When does a sanding disc fail on a random orbital sander?

A disc fails when it will not stay on the pad, when it clogs, or when it is the wrong grain or grade for the material. Most of these failures trace back to the pad or the setup rather than the disc itself.

• Disc flies off or slips. The usual causes are a worn or crushed hook face, dust on the pad, poor alignment or a worn loop backing on the disc. Clean the hook face first; if clean discs still detach, the hook surface or pad needs replacing.
• Clogging on finishes and resinous wood. Paint, sealer and resin load the disc. A stearate coating is an anti-loading layer for exactly that, not an abrasive in its own right.
• Dust building up under the disc. Holes out of line with the pad block extraction. Re-centre the disc or switch to a mesh disc.
• Rounded edges on flat panels. A soft pad or interface pad follows contours. For levelling flat surfaces, PSA's stiffer bond is the system preferred in the sources; an interface pad is for contours and protecting the sander pad.
• Wrong sander size. None of the picks fits a 150 mm pad.

For the whole range of buyer comparisons, see the accessory buying guides index. To confirm the pad size and hole count of your own sander, use the tool accessory lookup.

08Questions readers ask