Prism99

Just want to mention that dense machine quilting with polyester thread does not seem to affect softness and drape at all, in my experience. This seems to be true even when the polyester thread is not fine. I have quilted densely with Glide thread, for example, which is a 40 wt thread, and was surprised it did not stiffen the quilt. Cotton thread when densely machine quilted, on the other hand, can stiffen up a quilt a lot. I once made the mistake of stipple quilting a doll quilt with 50/3 cotton thread and it came out stiff as a board! Fine polyester thread and fine silk thread, in my opinion, are better for dense machine quilting than cotton thread.

For hand quilting, cotton thread works well for the reason mentioned above -- less thread is used. In addition, if you think about it, machine stitches "lock" together so the stitches themselves do not move. In hand quilting, a running stitch is used, which means that there is "give" in the quilting lines. I'm pretty sure this contributes to the softness of hand quilting as well.

I agree about hand quilting and washing contributing to softness. About 30 years ago I hand quilted a baby quilt that was used by the mother and frequently washed and dried in the washing machine. Almost 20 years later I was able to handle the quilt, which had obviously been well-loved and well-used. The binding had frayed along the edges. What was remarkable for me was the quilt's softness. It was like rubbing a cloud against my face! In that particular quilt I had used Mountain Mist Blue Ribbon 100% cotton batting. (Note: this is not a batting I recommend for hand quilting, as it is relatively hard to needle.) This batting started out as softer than, say, Warm and Natural, but it was nowhere near as soft at the beginning as after 15 years or so of machine washings. I suspect most cotton battings will soften up with multiple washings, but I'm thinking those that start out with a stiffer drape will probably never soften up as much as others.