How big should the balloon be as it fills with water?

Wintercraft balloons are very strong.  Only under very rare circumstances would one burst when making a globe to fit on the Wintercraft Large Freezing Base.   

In general, the balloon should be filled until it rests comfortably on the freezing base (it should not wobble or roll off).  

For a small base a balloon should be filled to about 8-10" in diameter or about 10-14 lbs of water. 

For a large base a balloon should be filled to about 11-13" in diameter or about 20-40 lbs of water. 

TIP: Fill the balloon in a laundry tub!

If you are feeling adventurous, keep in mind that these heavy-weight balloons will burst around 65+ pounds of water …