OK..here is what I do with ultra cote. I use the windex method, and squeegie out the extra liquid to remove as many bubbles as possible. HOWEVER, I read in a thread on RCU some time ago that said to put some holes in the covering under where you are doing your overlay. These allow the gasses that are created to escape into open areas under the first covering. I have a 4*60 and added wide stripes under the wing to help tell top from bottom. I put several pin holes in the RED (original covering) between the ribs. I was attaching the wide stripes from rib to rib. By having the holes under the top covering, the gas escaped and left a real smooth surface. I haven't seen any trouble with this method yet. I have attached a picture, all of the yellow that you see is the added part.