Engine Turning & Guilloché - an explanation
Other motifs have specific names as well e.g. "moire" ( mwah-ray ), meaning numerous parallel wavy bands or lines. Examples of other designs are shown at the RGM Watch Co. website.
Current usage in reference to enamels however has the term guilloché almost universally describing just about any sort of vitreous enamelling over regular, repetitive groundplate patterning. The practise is rampant in the antique community and amongst Western enamellers generally.
However, the use of large unrelieved areas of transparent or translucent enamels of one colour over a machine-engraved ( engine turned ), hand-worked ( flinqued - engraved or chiselled ), stamped, cast or otherwise altered groundplate is enamelling "en plein" ( ahn plahn ).
Cast or stamped reproductions of an engine-turned design can not be described as engine-turning although they are often passed off as such.
"Imagine being able to do on metal what you can do on paper with a ruler, compass, French curves, or any other drawing instrument. Then consider hand engraving on metal as freehand drawing.
The engine turning process is basically a set of drawing instruments for engraving lines on metal. It works slightly differently - for example the cutting tool remains stationary and the workpiece is moved against it, but the principle is really very similar.
The link above is to the RGM Watch Co. website once again - you will see there a lucid explanation of engine turning for very complex high-grade watch dials.
The straight line machine is a sophisticated ruler that can cut parallel lines, straight or wavy and can also cut straight or wavy lines radiating from a point. In addition it is able to do this on surfaces which are curved.
The circular machine provides the complementary compass actions, with the addition of wavy circles or arcs, and again can deal with three dimensional objects, in particular cylinders, cones and spheres, none of which have to be regular in particular."
( I can't remember whether I lifted the text above or cobbled it together myself - if I pinched it my thanks to the writer < g > - if I didn't, I could do with some medium-term memory therapy. Ed. )
Additionally, all you could ever hope to want to know about Engine Turning ( and more! ) you will find at the excellently-informative website of Pledge & Aldworth, maintained by the multi-skilled Mr. David Pledge, engine-turner and inventor extraordinaire.
More information about other important uses of guilloché patterns can be found at Eric Weisstein's "World of Mathematics".
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