Floor Sanding Edger Discs 7-Inch: VA vs Norton vs 3M

For most edger work: Mercer zirconia on cloth at 36 grit, Virginia Abrasives PSA at 60 and 80, and Mercer again at 100. That split is not brand loyalty. VA is the better buy at the middle grits and the cheaper one, but its 36-grit disc is paper-backed and draws repeated tearing complaints, and both of its 100-grit listings fall below our 4.0-star floor. We recommend the disc that survives the pass. Match the edger grit to the drum grit at every stage. Budget 4 to 6 discs per grit for a 200 sq ft room. This guide compares the three brands honestly, walks the PSA-vs-hook-and-loop decision, and gives per-grit picks. For Clarke Super 7R machine setup, see our 7R guide.

Three pre-rental checks

Same as for any floor sanding rental:

1. Engineered vs solid? Check.
2. Pre-1978 house? Lead test first. Why.
3. Two separate 15A circuits? Setup.

Why edger discs matter

Drum sanders cannot reach within 6–12 inches of walls. Without proper edge sanding, a visible line appears around the room perimeter where the wall edge remains unfinished while the center is polished. Two-tone effect, immediately identifiable as amateur work.

For machine setup and technique — including the variable-speed dial that most operators ignore — see our Clarke Super 7R guide.

Machine compatibility

7-inch discs fit:

Machine	Spindle	Notes
Clarke Super 7R (modern)	7/8” center hole	Most common rental edger
Clarke Super 7R (older)	5/16” center hole	Verify spindle before buying
Hiretech HT7	7/8” center hole	Same disc size
Other 7-inch orbital edgers	varies	Check the machine before ordering

Confirm spindle size before purchase. Wrong center hole = wasted trip to the supplier.

Honest cross-brand comparison

Brand	Backing	Where it wins	Price per disc	Honest verdict
Virginia Abrasives	Paper, semi-closed coat	60 and 80 grit	Cheapest, under a dollar in the 50-disc box	The value pick at the middle grits, and the one we buy. Its 36-grit disc is the weak spot: paper backing tears under edger pressure and the listing carries repeated complaints about it.
Mercer	Zirconia on cloth	36 and 100 grit	About $1.66 at 36, about 72 cents at 100	Cloth backing survives the first pass, which is where paper fails. Also the only option at 100 grit that clears our rating floor.
Norton	Closed coat	Finish grits, in principle	Not comparable	Genuinely good abrasive, but Norton does not list 7 × 7/8 floor edger discs on Amazon, so we cannot link one. Buy it through a flooring distributor if you want it.
3M	Closed coat	Fallback	Not comparable	Same problem as Norton. No 7 × 7/8 edger listing on Amazon.

The honest take: buy VA at 60 and 80 because it is cheaper and cuts well, and Mercer at 36 and 100 because VA’s discs at those two grits either tear or fall below our rating floor. Norton and 3M make good abrasive for this machine but do not sell it in this size on Amazon, so treat them as distributor purchases rather than something you can add to a cart today. Prices and ratings verified August 2026.

Picks by user mode

Your situation	Cut grits (36, 60, 80)	Finishing grit (100)	Where to buy
One floor, one weekend, oil-based clear	Mercer zirconia at 36, VA PSA above it	Skip 100, finish at 80	Mercer 36 · VA 60
One floor, one weekend, water-based or stain	VA PSA at 60 and 80, Mercer at 36	Mercer 100	VA Amazon + Norton 7” search
Light pro doing 3–6 floors a year	VA hook-and-loop at 60 and 80 (faster disc changes save 5–10 min per change)	Mercer 100	VA hook-and-loop search + Norton search
Hard species (hickory, jatoba, hard maple)	Virginia Abrasives Monster ceramic discs (or Norton SG / 3M Cubitron)	Monster ceramic	VA Monster line · VA store

The Norton links carry the same affiliate tag as ours — we earn the same small commission whichever brand you pick, so the picks are by fit, not payout. The Monster line link goes to the manufacturer’s site and earns us nothing.

PSA vs hook-and-loop — the format decision

PSA (pressure-sensitive adhesive)

• Adhesive backing sticks directly to a metal backing plate
• ~$2–4 per disc at loose-disc retail; VA’s 50-disc contractor boxes pencil under a dollar a disc (the 36-grit box runs ~$48). Either way, 20–30% cheaper than hook-and-loop
• 5–10 minutes per disc change (clean old adhesive, install new, wait for set)
• Adhesive cleanup required between grit changes
• Industry standard at rental shops — most rental 7Rs ship PSA-ready

Hook-and-loop (Velcro-style)

• Velcro-like backing on a hook-and-loop pad
• ~$3–5 per disc, but the pad itself is ~$10–20 one-time cost
• 30 seconds per disc change
• No adhesive cleanup
• Pads last indefinitely; discs reuse cleanly for next-grit work

Which should you buy

For a typical refinish with 3–4 grit passes — hook-and-loop is worth it. You change discs at least 6–8 times. The 5–10 minute time savings per change adds up to 30–80 minutes per job.

For a single-grit screening pass, PSA is fine.

Pro tip: ask the rental shop if their 7R is hook-and-loop ready, or if they can install a hook-and-loop pad for a small fee. Most do this now.

Why semi-closed/open coat for cut grits and closed for finish

Cut grits 36, 60, 80 — semi-closed or open coat

Open-coat discs cover ~60% of the backing with grit and leave dust-clearance gaps; semi-closed coat sits just below fully closed but keeps enough gap to resist loading. On old polyurethane or any gummy material, that clearance lets dust fall away instead of welding into the abrasive — a loading-resistant disc at 36 grit on a finished floor lasts far longer than a fully closed-coat disc at the same grit.

VA’s floor line is semi-closed coat — VA credits the semi-closed coating with resisting loading from old coatings, which covers the cut grits well. This is where VA earns its contractor-default reputation.

Closed coat at 100/120

Closed-coat discs pack 90–100% grit coverage. More grain = more cutting per pass on dense, clean materials. On bare wood at the finishing stage (no finish loading the disc), closed-coat geometry cuts a more uniform scratch pattern.

Under water-based polyurethane — which is transparent — the more uniform scratch pattern reads as a smoother perimeter. For stain work, uniform scratches absorb stain more evenly and reduce blotchy edges where the edger ran.

Norton’s closed-coat 100 grit is denser and more consistent than VA’s. Worth the upgrade for the final pass when finish quality matters.

Disc quantity per grit

Room size	36 grit	60 grit	80 grit	100 grit
250 sq ft	2–3	2–3	2–3	1–2
400 sq ft	3–4	3–4	3–4	2–3
600 sq ft	5–6	5–6	5–6	3–4

Edger discs wear faster than drum sheets because the 7R operates at high pressure and the smaller disc traces every corner. Budget generously. You can reuse hook-and-loop discs at the next-grit level if they’re not fully worn.

VA’s 60-grit listing is a 50-disc box, far more than one job needs, but per-disc cost beats loose-disc retail several times over and the spares carry to the next floor. At 100 grit the Mercer disc comes 25 to a box at about 72 cents each. For the 36-grit first pass, the Mercer zirconia disc comes 25 to a box at a higher price per disc and a cloth backing that survives the pass: Mercer 36 grit · VA 60 grit · 100 grit.

For the full sheet calculator with species multipliers and worked examples, see our sheet calculator.

Common mistakes

Not matching edger grit to drum grit

If the drum just ran 80 grit on the field, the edger needs to run 80 on the perimeter at the same time. Mismatching = visible color and scratch difference at the wall edge under finish.

Tilting the disc

The disc must stay flat against the floor. Tilting creates swirl marks. The most common technique failure on the 7R.

Over-pressing at the wall

The 7R is heavy enough; let it work. Pressing harder doesn’t cut faster — it just gouges the floor edge and tears discs.

Skipping inside corners

The 7-inch disc can’t reach a 90° angle. After the edger pass, hand-sand inside corners with a sanding block at matching grit. 15 minutes per room. Transforms the final appearance.

Worn discs left in service

A worn disc doesn’t cut; it burnishes. Burnished spots reject stain and create blotches. Replace discs when they stop cutting aggressively.

Current prices

Why a competitor brand at 36 grit. Virginia Abrasives makes the rest of the line we recommend, and this site discloses that its author sits on VA’s board. The 36-grit VA edger disc is paper-backed and draws repeated tearing complaints on Amazon, which matches the failure the 7R produces at high pressure. We recommend the disc that holds up. Both links pay the same referral either way, so the pick is not a commission decision.

Prices pulled from Amazon at publish; verify before ordering. Amazon Associate disclosure: we earn from qualifying purchases.

For machine setup, variable speed, and technique

This article covers the discs. For Clarke Super 7R machine specifics — center hole sizing, variable-speed RPM by grit, rental inspection, edging technique — see our Super 7R machine guide. For the full process see how to sand hardwood floors.

Match the edger grit to the drum grit at every stage. Run light pressure. Keep moving. The disc does the work — your job is not to fight it.

Matt.