Quick Answer

Grind smooth by following the grit sequence one step at a time, changing direction between grits, keeping pads flat with even pressure, and vacuuming between passes. Scratches almost always come from skipped grits, dirty pads or uneven pressure.

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Follow the Sequence - Never Skip

Each grit only removes the scratches of the one before it. Skipping from 16# to 100# leaves deep 16# marks that no fine grit can fully remove. Step through 16# - 30/40# - 60/80# - 100/120# and beyond.

Change Direction Between Grits

Grind north-south with one grit, east-west with the next. Cross-cut scratches are easier to see and easier to remove, and any missed marks show up before polishing instead of after.

Keep the Machine Flat and Even

Edge pressure cuts deeper and leaves swirl marks. Run the machine flat, use steady speed, and overlap passes by a third. Let the tool do the cutting - pushing harder usually makes scratches worse.

Keep Pads and Floor Clean

Loaded or contaminated pads scratch the surface you just smoothed. Vacuum between grit changes and inspect pads for embedded debris. On fine grits, even a few grains of sand can score the floor.

Check with Raking Light

After each grit, look at the floor with light from a low angle. If you see directional scratches, stay on the current grit. Only move up when the scratch pattern looks uniform and fine.

Frequently Asked Questions

Q: Can I fix scratches after polishing?

A>Yes - re-grind at 100#-200#, then step back up through the sequence to the final grit.

Q: Why do I see new scratches on the fine grits?

A>Usually dirt, a contaminated pad, or dust from another area blowing onto the floor.

Q: How many passes per grit?

A>One to two full overlapping passes with a planetary machine on most floors.

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Conclusion

Smooth concrete is the result of discipline: no skipped grits, clean pads, even pressure and honest light checks. Follow the system and the scratches disappear.