So grateful for all the posters here. I have often wished I could run 12wt through my machine on top for some special art quilting. I had read on Aurifil's site that it's for hand stitching & had heard about it being used for bobbin work, but never realized you can used it on top with some minor adjustments. I found this blurb today on Fat Quarter Shop's website:
Aurifil 12 wt thread is ideal for hand quilting, big stitch hand quilting and machine quilting. 12 weight thread creates a more defined and often primitive look. It's great for designs that use a longer stitch length if using a machine. When machine quilting with 12 wt thread, use 40 wt in the bobbin, increase your stitch length, lower your tension, use Topstitch size 90 needles and stitch slowly.
So of course, now I want to go to LQS to buy some 12wt thread. Let's see if I can get out of there without buying 6 more things that weren't on my list.