What would hair wire mic ?

Hi to all, It seems to me that small awg stranded wire like 18 or 20 the individual strands are about the same size as the very small wire found on small transformers and things.So I dont understand why some yards advertise no hair wire but say nothing about small stranded wire.You would think if they found a way to make hair wire they could find a way to reuse it,like mash it in a 100 ton press or something so it does'nt vaporize when melting it.Thanks for any input.