I have also found it helpful to do the base color (yellow in this case) in a higher temp covering like Monokote and then the stripes (black in this case) in a lower temp covering like Ultracote, tower kote, or Econokote. This way you can set the iron at a lower temp for the stripes and cut down the air bubbling problum. The Windex "trick" only works on Monokote brand and I understand that adding extra ammonia to the Windex helps also.