The piece was covered with dust, partly melted into the surface. I don't use nylon thread. I want my quilting lines to be very visible, and nylon thread does tend to break, according to what I've heard. Also, you should know that I don't drop the feed dog, even though that is fun. Somehow it seems too easy, sort of like cheating.
Good basting is the key to a well-quilted surface.
I tackle the quilting by anchoring large sections at first, so that in the first hour or two all segments of the quilt except for the border have some quilting in them. Then I work in quadrants, moving in a balanced manner from section to section, to prevent the quilt from stretching. Then I focus on texturing detailed areas. Finally, the border is quilted. My first response would be the quilts I cherish, from a bow tie quilt made in the 1950s by my Aunt Judith to a top by Anna Williams that I purchased this year.