Knurled wire is drawn precious or base-metal wire whose surface has been textured with a regular pattern of axial, helical, or cross-cut ridges, produced by rolling the wire between knurling dies after the final draw. It is supplied to the jewellery trade in fine, half-round, and rectangular sections in gold, silver and platinum, and is used principally as a decorative element in chain links, ring shanks, bezel surrounds, and openwork galleries. The use of textured wire dates back to mediaeval European and Eastern Mediterranean goldsmithing and the modern knurled wire trade is continuous with that lineage through the granulated and beaded wires of the Etruscan revival workshops of the nineteenth century.

Production

Knurled wire is produced by passing finished drawn wire through a pair of knurling rolls whose surfaces carry the inverse of the desired pattern. The rolls displace metal from the wire surface into the pattern voids, leaving the wire with a regular ridged or beaded exterior. Common patterns are fine axial ridges, which read as a comb-like profile when viewed from the side; close helical ridges, sometimes termed cable wire; and small spaced beads, in which a series of fine pinch points along the wire produce a string-of-pearls appearance closely related to true beaded wire. The final wire diameter is slightly larger than the pre-knurling diameter because of metal displacement.

Materials and gauge

Knurled wire is supplied in fine silver, sterling silver, 18-carat and 14-carat yellow, white and rose gold, and platinum. Diameters range from 0.5 millimetre, used as fine bezel wire, up to around 3 millimetres for substantial decorative shank work. Argentium silver is used in modern hand work because of its tarnish resistance.

Use in jewellery

In bench jewellery, knurled wire is used principally as a decorative bordering element. A short length of fine knurled wire soldered around the rim of a bezel produces an effect closely related to milgrain edging but with a coarser, more deliberate pattern. Knurled wire is also used to form the openwork galleries of antique-style settings, the decorative side panels of bracelet links, and the patterned bands of textured rings. As a chain link, knurled wire produces a heavier and more textural visual effect than smooth wire of the same gauge, and is used in heavy curb and rope chains for that reason.

Care

Knurled wire shares the cleaning issues of all textured surfaces in jewellery: skin oils, soap, and polishing-cloth residue accumulate in the recesses of the pattern and dull the surface. Steam cleaning is preferred over ultrasonic for fine work; for heavier knurled wire, ultrasonic cleaning followed by steam is acceptable. Tarnish on knurled silver wire is difficult to remove by polishing cloth alone and usually requires a chemical dip or a soft brush worked into the pattern, followed by re-polishing of the high points.