Guilloche

Guilloché (/ɡɪˈloʊʃ/),(or guilloche) is a decorative technique in which a very precise, intricate and repetitive pattern is mechanically engraved into an underlying material via engine turning, which uses a machine of the same name, also called a rose engine lathe. This mechanical technique improved on more time-consuming designs achieved by hand and allowed for greater delicacy, precision, and closeness of line, as well as greater speed.

The term "guilloche" is also used more generally for repetitive architectural patterns of intersecting or overlapping spirals or other shapes, as used in the Ancient Near East, classical Greece and Rome and neo-classical architecture, and Early Medieval interlace decoration in Anglo-Saxon art and elsewhere. Medieval Cosmatesque stone inlay designs with two ribbons winding around a series of regular central points are very often called guilloche. These central points are often blank, but may contain a figure, such as a rose. These senses are a back-formation from the engraving guilloché, so called because the architectural motifs resemble the designs produced by later guilloché techniques.

The name, as guilloché, is French, dating back at least to the 1770s, and is often said to be called after a French engineer named Guillot, who invented a tool or turning machine. However no dates nor first name are provided for this shadowy figure, and many dictionaries seem suspicious of his existence.

Engine turning machines were first used in the 1500–1600s on soft materials like ivory and wood and in the 18th century it was adopted for metal such as gold and silver. Some accounts give the credit of developing tightly-packed engraved guilloché decoration to the Nuremberg glass-making dynasty of the Schwanhardt family in the 17th century, using a wheel to engrave the glass.

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