I remember being amazed the first time I saw custom balloons being printed. I had no idea that each balloon must be inflated before printing. Each balloon is inflated one by one and then silk screened. Because printed balloons are used inflated, the balloon must be inflated to almost full size in order for the imprint to look clean and crisp. If the balloon was printed deflated, the image would fade when the balloon is inflated for use.
After the custom balloon is printed, the balloon must remain inflated for some time to dry the ink image. Then the balloon must be dried in a dryer to further cure the ink and remove the wrinkles from the balloon caused by the inflation. Then you have a perfectly printed custom balloon ready for your next party or event.
The other reason that the balloon are printed inflated are to remove any balloons that may have holes or imperfections.