I think this thread is awesome for all types of machine quilting (free motion, ruler quilting, longarm quilting, and walking foot quilting) plus machine embroidery and applique.
Isacord is a 40 weight polyester thread and I always use it in both the top and bobbin of my machine. Mismatching threads is a good way to end up like Betty above! It's so much easier to find good tension and stitches if you use the same thread, in the same color, in both the top and bobbin of your machine.
And just in case you're wondering, no, I don't use Isacord for quilt piecing.
This thread is slippery and tends to unravel unless properly secured. For this reason, I don't piece my quilt blocks with Isacord. I use a 100% cotton thread instead.
