I am doing a complicated Ultra Cote covering pattern on my new Sumptin Extra. My problem is when the covering is being put down on top of another layer of Ultra Cote. I am sure everyone has done this. When you put a small design over a covered surface you are doing what I am trying to do. My problem is bubbles between the 2 layers. I was told to turn the iron down below 200 degrees and try to work from the middle out. That all helps, but I sure get bubbles. I pick them with a #11 blade and re-seal the area, but you can still see the impression in the covering. Are there any sure fire ways of covering over covering without bubbles between?