The invention relates to a device for treating wire material, comprising at least one station consisting of two disc-shaped substrates. The surfaces of said substrates face each other and overlap, clamping the wire material with a changing surface condition. The substrate surfaces (C1, C2) overlap except for at least one visual inspection zone (K), which remains exposed for viewing on at least one substrate surface (C1) and likewise makes contact with the wire material (D). The surface condition of said zone is essentially the same as the wire contact area (F) of the overlapped remainder of said substrate surface (C1).