How should I clean mud and paint off an extension cord?

For mud, wipe it dry with a rag or knock off caked-on bits with a gloved hand or dry brush — no water needed. For paint, use mineral spirits or isopropyl alcohol on a rag; they evaporate fast and won’t harm standard rubber or vinyl insulation. Avoid acetone, lacquer thinner, or strong solvents — they can soften or crack the jacket. Test a hidden spot first, and don’t let solvent sit for minutes.