I just got finished putting my black background on my 75gal tank. I used the oil product called Sea View. So here is my story and tip:
After coating the plastic laminated background with the oil with the help of a friend, we placed it onto the tank glass. After 30+ minutes of trying to get the air bubles trapped between the background and glass I noticed something. Every time along the top when I got rid of the bubles they would always reform. However the bottome looked fine. I finally figured it out. The top edge of the plastic background was cut unevenly. I did it to myself when I tryied cutting the background to fit the size of my glass.
So my tip is make sure your background is cut precisely before trying to used SeaView. It will save you a lot of wasted time!
BTW the background now looks great!!!