heat shrunk under side of upper wing 250, 300, and 350 degrees. heat formed in aileron cove. Over the past two weeks, I have worked the upper wing although not logging the progress.Lots of heat shrinkng around the bows as expected. Ran out of -3 fabric and picked up the new -4. Definite difference. More difficult to get adhesive to wet through. So, thinned a bit more.