Selecting the right copper yarn requires a balance between electrical conductivity, antimicrobial efficacy, and mechanical strength. For textile use, ensure the copper is permanently bonded to the polymer matrix (like nylon or polyester) rather than just surface-coated, as this prevents the copper from washing out. For industrial shielding, verify the purity of the copper (typically 99.9%) and the denier/thickness to ensure it meets the required tensile strength for high-speed knitting or weaving machines.