Quick Answer

A typical concrete grinding sequence runs 16# (or 6#) metal bond for levelling, then 30/40#, 60/80#, 100/120# and 150-200# before switching to resin or hybrid pads. Each grit removes the scratches of the previous one, so progression must be one step at a time.

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Choosing the Starting Grit

• 6#: heavy levelling, deep scratches, thick coating residue
• 16#: standard first pass on most floors
• 30/40#: floors already reasonably flat, thin coatings

The Full Ladder

• 6# or 16# - cut and level
• 30/40# - remove first-pass scratches
• 60/80# - smooth the surface, uniform scratch pattern
• 100/120# - honing, surface starts to feel smooth
• 150# - 200# - fine honing before resin
• 400#+ resin or hybrid - transition to polishing

How to Read the Scratch Pattern

Check the floor under raking light. If you still see coarse directional scratches after a grit change, the previous grit did not do its full pass. Grind longer, or change direction so the new grit cuts across the old marks.

Common Sequence Mistakes

• Skipping grits to save time: leaves deep scratches that show after polishing
• Changing grit too early: wastes the new grit fighting old marks
• Changing direction randomly: scratch pattern becomes hard to read

Frequently Asked Questions

Q: How many passes per grit?

A>Usually 1-2 full passes with a planetary machine; more if the floor is rough.

Q: When do I switch from metal to resin?

A>Around 100/120# to 200#, once the surface feels smooth and coarse marks are gone.

Q: Do I always start at 16#?

A>No. Start coarser for rough floors, finer for already-smooth slabs.

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Conclusion

Progress one grit at a time, read the scratch pattern honestly, and let the floor tell you when to change. The sequence is the backbone of every good polished concrete job.