Electroplating station (S) has a mesh (11) located at a throat section (12) of passageway (4) shortly before the start of the guide (7) thereby to cause and/or enhance the production of vortices by guide (7) and/or the serrations. At its narrowest, throat (12) is about 5 x 10 -3 metres across. The mesh is a polyester mesh N8 type of 34.6 threads 10" 2 metres with a thread diameter of 1.04 x 10 -4 metres giving a maximum open area of 38 %. In a variant, a mesh (13) is located further upstream in passageway (4) as an alternative and/or as an addition to mesh (11). When both meshes (11 and 13) are provided, they can be identical or of different characteristics, for example mesh (13) may be of a coarser form with a greater open area and/or finer thread diameter, and mesh (11) may be of a finer form with less open area and/or thicker thread diameter. In further variants, mesh (11) and/or mesh (13) may extend over only part of the passageway (4) or may be replaced by a rigid grid, a series of elongate bars with corresponding elongate apertures, or other orificed structure.