High Voltage Winding Wire Transformer Enameled Flat Aluminum Wire 2-22.5mm is a aluminum wire mainly used for windings with contiguous turns. Enamel is in fact a very resistant insulator mechanically, thermally and electrically. In addition to ordinary enamel there is solderable polyurethane enamel which is suitable for very large diameter wires (from 0.16 mm) very difficult to mechanically pickle. Pickling occurs around 400-500 ¡ã C.