Originally Posted by redmadder
I like wool yarn. Have used embroidery thread, pearl cotton and acrylic yarn. They all work but some work themselves loose. Wool never does.
I have always used DMC embroidery thread, all 6 strands. I like it because I can match the colors to whichever square that I am tying but I did have some work themselves loose after washing the quilt, one time. Just make sure you do a good tight knot.