Stick and flux-cored welding leave a layer of slag over the bead, which must come off before the next pass and before painting. A chipping hammer has a point at one end for getting under the slag and a chisel at the other for running along the bead.
Most have a coiled spring handle, which absorbs the shock. Welding over slag traps it in the joint as an inclusion — a genuine defect and one of the commonest reasons multi-pass stick welds fail.
The questions welders ask
Is a wire brush enough?
For the residue after chipping, yes; on its own, no. Slag on a properly hot stick weld often lifts in a single curl once tapped, and the brush then cleans the surface. On a cooler weld it clings and needs the hammer.
Last reviewed 2026-08-14