First scope the wall – mark the exact 8 by 8 spot, keep the surrounding concrete intact, and check for any embedded rebar. Then we’ll use a controlled explosive charge, say a small amount of C4 or ANFO, set in a drilled hole about 3 inches deep and 6 inches from the edge. The charge should be centered in the middle of the 8‑by‑8, but angled 10 degrees outward so the blast pushes the concrete outward rather than inward, keeping the edges clean. After the detonation, do a quick clean with a pressure washer to remove any residue, and you’ll have a fresh, even surface ready for paint. Safety first – keep a 20‑foot radius clear, and double‑check the surrounding structures before we go.