You just keep the iron between a 1/16 and 1/8 of an inch off the covering if you are just shrinking or removing sags, wrinkles and bubbles. If bubbles, take a pin and poke a few holes in the covering to allow the gas to get out. The glue/pigment usually only gets on an iron when you go over edges but if you get any on your iron for some reason just use alcohol or acetone to remove it after the iron cools.