This specification covers tinned hard-drawn and medium-hard-drawn round copper wire for electrical properties. The tinned wire shall be made by coating hard-drawn and medium-hard-drawn copper wire with commercially pure tin. The copper shall be of such quality and purity that the finished product shall have the properties and characteristics prescribed in this specification. The tin coating shall consist of a smooth continuous layer, firmly adhering to the surface of the copper. The wire shall be free from all imperfections not consistent with the best commercial practice. The tinned wire shall conform to the requirements as to the tensile properties prescribed. Tension tests shall be made on representative samples. The elongation of the wire shall be determined as the permanent increase in length due to the breaking of the wire in tension, measured between gage marks. Electrical resistivity shall be determined by resistance measurements made in accordance with the test method prescribed in this specification. The continuity of coating on the wire shall be determined by the sodium polysulfide test. The specimens shall be thoroughly cleaned by immersion in a suitable solvent for the appropriate time required to remove oil or grease from surface; then removed and wiped dry with clean, soft cloth. Mechanical test for adhesion of coating shall be performed. Any cracking or parting of the coating in the area shown by blackening of the copper shall be cause for rejection.