I won't tie quilts with yarn anymore. Yarn ties were my preferred method when I first started quilting. However, I found some yarn ravelled, some un-tied and some melted. If I ever tie again, I'll use perle cotton. I actually find it faster to machine quilt now than to tie a quilt and I think the machine quilting stands up better to repeat washings. I had some of my tied quilts that had shifted batting or ties pulling out after many washes.