From the link @PhotonWrangler posted above:
The balloons can come in several forms. Some enthusiasts still use common, Mylar party balloons, with a set of published calculations to determine the amount of gas to inject. But the round-shaped Mylar balloons often are unable to ascend higher than 20,000-30,000 ft., so some pico balloonists have upgraded to different materials.
I wonder if mylar party balloons will be a thing of the past, and be outlawed.
The balloons can come in several forms. Some enthusiasts still use common, Mylar party balloons, with a set of published calculations to determine the amount of gas to inject. But the round-shaped Mylar balloons often are unable to ascend higher than 20,000-30,000 ft., so some pico balloonists have upgraded to different materials.
I wonder if mylar party balloons will be a thing of the past, and be outlawed.