You can write on the Bubble Balloon using a pen, paint, or permanent marker. Make sure the pen is not water-soluble. Keep in mind the dry time of the pen you are using, since it is very easy to smudge a design that is not yet dried.
You can write on a Bubble Balloon when inflated or uninflated. Since the balloons are see-through, designs can be traced using a piece of paper. If you want your messages to be visible, do not design all the way to the edge of the balloon. The last 2 to 3 inches of the design will wrap around the balloon.
Uninflated balloons are easier to write on, but the ink might stretch once inflated. This may result in the balloon looking different from what was initially expected. Writing on balloons can take some practice. You might want to order a few extra balloons to test out your skills.