Bubbling in your laminate film is a common problem, and it usually a product of moisture in the substrate. This problem generally occurs in areas of the country with higher humidity. Most of the time it is a drying or curing problem with the substrate. When you laminate something that hasn't properly cured the moisture comes out of the substrate and is encapsulated in the laminate but has know where to go leaving bubbles in your laminate. Leaving the substrate to cure for 24 hours before lamination usually solves this problem. A de-humidifier can also help with this problem in certain areas of the country.