I used to use invisible thread, but not anymore. I've found that a neutral color works just as well, and won't disintegrate over time. I usually use a light-to-medium grey to quilt all my t-shirt quilts. The grey seems to go lighter on the light blocks and darker on the dark blocks. It's less noticeable to the eye than a cream. I tried sewing over the rubberized logos - once. Never again. It was a PIA and looked awful. Plus, I find that leaving the logos open makes them pop. Looks much better. I don't even sew over the logos on non-rubberized shirts anymore. It just looks better. bpowers64, you use iron-on interfacing, so yes it does stay on.