I’d known about this technique for years but never tried it – more fool me. Anyway, I thought I’d try it and now I won’t do my collar peaks any other way.
Mark the seam for accuracy, I use a 1cm seam and a heat erasable pen (the heat from the iron removes it).
Have two lengths of thread ready and sew the seam.
Sew to one stitch before the mark, I shorten the stitch length about 2cm from the mark. Lift the presser foot and put the thread next to the last stitch.
Stitch once to secure the thread and put both ends out of the way between the fabric layers.
Pivot on the markings and sew to the other end, lengthening the stitch to normal after 2cm. Repeat with the other peak.
Trim the corners and turn out.
The two threads are now inside the collar, take both together and pull gently.
A perfect peak. Hold one length of the thread and pull to remove.
The difference between a pulled peak (top) and a prodded peak (bottom).