Tapered trailing is, as its name suggests, a tapered version of trailing. It consists of a core of laid threads which are completely covered with small couching stitches. The number of padding threads varies so that the shape alters in thickness: you can start with any number of core threads and work down to very few or none.
Begin working your trailing stitches. Angle your needle out from under the core threads and back underneath them with each stitch.
To gradually taper the line, separate the core threads, lift the top threads out of the way and carefully snip a few of the strands closest to the fabric.
Continue to couch over the remaining core threads, holding the core threads in place to keep them taut. Make sure no fluff shows where the threads were cut.
Repeat the trimming process as many times as necessary, to gradually taper your line. Make sure you always trim the underneath threads.
When you are near the end of the line, take your last core thread(s) to the back of the fabric, finish stitching to the end and secure your couching thread.
Structure of stitch
Various Authors, The Royal School of Needlework Book of Embroidery (2018) , p.333
Isabella Mary Beeton, 'Beeton’s Book of Needlework', Beeton's Book of Needlework (1870). Available at: http://www.beetonsbookofneedlework.com/ (Accessed: 01 December 2021)