Step 2 · Undercut the Edge (if necessary)

If the chip has sharp, feather-edged concrete, use a chisel and hammer to slightly undercut the edges of the damaged area. This creates a small 'keyway' or 'dovetail' shape that helps to lock the repair material in place. Aim for an undercut of about 1/4 inch deep. Brush away any dust created by this process.

Tools and Materials