When sourcing iron wire, you must prioritize wire gauge (diameter), tensile strength, and surface treatment. For construction or binding, annealed iron wire is preferred due to its high flexibility and elongation. For fencing or outdoor use, hot-dipped galvanized wire is essential, as it provides a thick zinc coating (typically 40-290g/m²) to prevent corrosion. Ensure the supplier provides a Mill Test Certificate (MTC) to verify the chemical composition, specifically the carbon content, which dictates the wire's hardness and ductility.