Thank you all for your advice! Based on it, I'll dampen my 2-row strips, iron them 'til dry, starch them and iron again. Fortunately I labeled each set in numerical order, and I know exactly how to sew them back together from the other end. (Oh, the virtues of being an experienced creator of bargello quilt tops!) If that doesn't work … hmmmmm … I'll probably consult y'all again.