In English Smocking, the Bar Stitch
is nothing more than the Satin Stitch worked vertically over
one or more pleats..
Hints:
Keep the stitch tension consistent, and don't
pull so tight that you distort the pleat. Here's
a trick to controlling the tension : insert a small
needle or pin along the pleat so that it hugs the
very tip of the pleat. Stitch around the needle,
pulling the thread tight. When you're done, pull
the needle out.
Stitch with a single strand. It's easier to get
a smooth appearance to the stitch than with multiple
strands.
A Bar can also be stitched over two
pleats, or even three :