Refinish Oak Floors: 36?60?100?120 Grit Sequence

Oak floors are tough, dense, and open-pored—beautiful when finished, but unforgiving if you skip steps during sanding. A successful refinish depends on following a strict grit progression: 36 ? 60 ? 100 ? 120. Each stage removes the scratches from the previous grit, levels the floor, and prepares the surface for stain or clear finish. Cut corners, and you’ll see chatter marks, swirl lines, or stain blotches under every ray of sunlight. Here’s how to do it right.

Why Sanding Progression Matters

Each grit in the sequence has a job: 36 removes finish and levels; 60 erases 36’s deep scratches; 100 smooths and refines; 120 tightens the scratch pattern for finishing. Skipping a grit means the next one works harder, loads faster, and leaves behind deep scars that show up later. On oak—a grainy, ring-porous wood—those scratches can look like black lines once stained.

Tools & Materials

• Drum or belt floor sander with 36, 60, 100, 120 grit belts
• Edger sander with matching discs for corners and edges
• Buffer/floor polisher with 120 grit screen for blending
• Shop vacuum with brush head, tack cloths
• Raking light to spot chatter and swirl
• PPE: respirator, ear protection, knee pads

Recommended Grit Sequence

• 36 grit — Heavy cut: remove finish, flatten cupped boards.
• 60 grit — Refine: erase 36 scratches, start leveling grain.
• 100 grit — Smooth: prep for clear or stain.
• 120 grit — Final pass: tight scratch for stain or waterborne topcoats.

Step-by-Step: Oak Floor Refinishing

1. Prep the room. Remove baseboards if possible, cover vents, and plastic off adjacent spaces. Vacuum debris so it doesn’t score the floor under the sander.
2. First cut at 36 grit. Sand diagonally across boards to flatten cupping and remove finish. On edges, use an edger with 36 grit (25-pack). Don’t linger—keep the sander moving to avoid divots.
3. Refine with 60 grit. Sand with the grain, overlapping each pass by 50%. Switch to 60 grit (50-pack) on both the drum and edger. This step erases 36’s scratches and sets a smoother field.
4. Smooth at 100 grit. Step to 100 grit (100-pack). Sand with the grain; edges and corners must match this grit too. Inspect under raking light—every 60 grit scratch should be gone.
5. Final 120 grit pass. Run a 120 grit screen under a buffer across the floor. This tightens the scratch pattern, blends drum/edger transitions, and leaves the floor stain-ready.
6. Vacuum & tack. Clean the floor twice—once after sanding, once after buffing. Dust left behind shows up as bumps under finish.
7. Finish application. Apply stain or sealer evenly, then topcoat with polyurethane. Follow recoat windows and de-nib lightly with 220 between coats.

Special Cases

Waterborne finishes: Stop at 120. They highlight scratches more than oil polys.
Stain-only jobs: Stop at 100 for better penetration, unless manufacturer specifies 120.
Engineered oak: Wear layer is thin—avoid aggressive cuts. Often start at 60 or 80 depending on thickness.

Pro Tips

• Always sand edges to the same grit as the field—mismatched edges show under stain.
• Keep the sander moving; stop marks are hard to erase.
• Check paper often—dull belts polish instead of cutting and leave swirl.
• Use raking light to spot chatter early; fix it at the current grit, not later.
• Vacuum between grits; stray 36 grit particles will cut scratches into later passes.

Aftercare

• Use felt pads under furniture after refinishing.
• Clean with pH-neutral wood cleaners; avoid water pooling.
• Recoat every 5–7 years; don’t wait for bare wood to show.

FAQs

• Can I skip 60 and jump from 36 to 100? No—100 won’t remove 36’s deep grooves. Always run 60.
• Is 150 better than 120? Not for floors. 150 can close pores too much, reducing stain uptake and adhesion.
• How do I fix swirl marks? Spot-sand with the current grit, then re-blend wide. Never hope the next grit hides them.
• Why do my edges look darker? They may not be sanded to the same grit as the field. Match grits carefully.

Video: Oak Floor Sanding Sequence

Closing: Oak floors reward discipline. Follow the grit ladder—36 ? 60 ? 100 ? 120—keep pressure even, and clean meticulously between steps. The result is a floor that takes stain evenly, shines under clear coats, and lasts for decades.