 Elastic piping is a thickened cord that you stitch to the neckline or between two seams to decorate. When you sew elastic to the neckline, take your elastic 10% shorter than the neckline, so the neckline fits nicely.

When used between 2 vertical seams, the elasticated piping does not need to be shorter, but with horizontal seams you also make the piping 10% shorter.