I tried my brother, Ed's, technique of removing the blue stuff with a soldering iron. Worked okay, but I get a little scratch on the aluminum. I'll dull my soldering iron tip a little. But I do like some skin protection that the blue stuff adds. I used a straight edge to get straight cuts in the blue stuff but that took a long time. So then I tried it free hand and you can't tell the difference in photos below. Free hand is much faster. I use the C-frame for almost all my dimpling instead of the squeezer. I have a small diameter female die that lets me do the ribs and stiffeners without bending the flange or interfering with the flange radius.