I wouldn't reccommend using yarm to tie quilts. The first quilts I made were tied with yarn that twisted, undid, ravelled, melted and some actually tore the blocks after shifting in the wash. Perle Cotton or embroidery cotton would work much better in my opinion. The other problem with yarn is that it needs a larger eyed needle which makes bigger holes in your quilt. As tying is not a quick technique, I now machine quilt all my quilts which I find is often faster and stands up to repeated washings and hard wear.