I just ordered this set myself. I don't do anything fancy...3 or 4 quilts a year but I am always buying thread to make a particular quilt. I haven't educated myself enough about thread, I guess, as I happily ordered this for everyday sewing use; piecing, applique and quilting which generally consists of cross-hatch, diagonals and SITD. Then I saw Tartan's reply and went into a panic! I honestly don't know what weight thread I'm using so when she said "if you use a lot of 12W" I thought, well now I have 70 spools of thread I can't use! So Please help me out a little here....can I use this great bargain 12w for my work???