Polishing grit is the number that tells you how coarse or fine a diamond abrasive is. Low numbers cut and remove material, and high numbers refine the surface to a shine.
Understanding Polishing Grit
Concrete polishing works like sanding wood, only with diamond tooling. Each pass uses a finer grit than the one before and removes the scratches left by the last step. Metal-bond diamonds do the heavy cutting at low grits. Resin-bond diamonds do the fine polishing at higher grits.
Typical Grit Sequence
A common path starts at 30 or 40 grit to remove coatings and level the slab, then moves through 70, 100, and 150 grit. After densifying, the floor goes through 200, 400, 800, 1500, and up to 3000 grit for high gloss. The exact steps depend on the floor condition and the finish the customer wants.
Grit and Final Finish
Level of shine and exposure of aggregate are different choices. Stopping at 100 or 200 grit gives a flat or satin look. Reaching 800 grit gives a medium gloss, and 1500 to 3000 grit gives a high gloss. The more you polish, the more reflective and stain resistant the floor becomes.
Practical Tips for Choosing Polishing Grit
Never jump more than about double the grit number between steps, or deep scratches will show later. Match the bond hardness to the hardness of the slab. Vacuum between passes so coarse grit does not scratch the next step. Always check the floor under good light before moving on.
Also Called
Diamond grit, Grit sequence
