Bullnose Step Slabs With a Diamond Profile Wheel, Then Sand Through the Grits

The Problem

Square-cut paving slabs stacked into steps read as exactly that — stacked slabs. The difference between that and a finished masonry look is mostly the edge: a rounded bullnose profile on the tread nose is what makes a step look made rather than assembled.

The Technique

A builder's process for bullnosing slab edges:

1. Mark a straight, consistent line along the top of the edge so the profile stays even across the slab.
2. Shape the edge with a diamond profile wheel on the grinder. Convention says work the slab upside down; this builder prefers face-up so he can watch the line — the wheel leaves a light black mark on the face, but it sands out completely at the finishing stage.
3. Keep the slab wet the whole time. Water controls dust and keeps the diamond cutting.
4. Don't force the wheel. Pressure dulls diamond tooling fast; let it grind at its own pace and make passes.
5. Sand through the grits: 60 to knock down the shaping marks, 120 to refine, 220 to finish — smooth from the top of the round-over to the bottom.