About the correct use of aluminum foil balloons

Note on using aluminum foil balloon:
If you want a balloon to float, you can't fill it with air, because air won't make the balloon float.  You need to use gases that are less dense than air to make the balloon fly.  Hydrogen and helium are commonly used in the market now, and both gases can make the balloon float.

However, in the process of use, it should be noted that hydrogen is different from helium.  Hydrogen is an inflammable and explosive gas, while helium is a relatively stable inert gas, so it is safer to use helium when making floating air balloons.  However, hydrogen balloons may explode or even catch fire when they encounter high temperature during use, so it must be paid attention to.