The two lines of stitching form a narrow channel into which a cord or thick yarn (usually cotton or wool) is threaded from the back. This creates a series of lines in relief. Sometimes the wadding is coloured, giving an extra dimension to the end result.
See also: trapunto
Digital soure of illustration (retrieved 28 May 2016).
Source: THOMAS, Mary (1936). Mary Thomas’s Embroidery Book, London: Hodder and Stroughton, p. 234.
GVE