Helium atoms are incredibly tiny, and the material of the balloon, whether it’s latex or foil, has microscopic pores that the helium atoms can slip through. This process is actually called “diffusion.” Over time, the helium molecules escape through these pores, causing the balloon to lose its buoyancy and eventually fall to the ground.
Latex Balloons vs. Foil Balloons
There are two main types of balloons: latex balloons and foil balloons. Latex balloons are made from a natural rubber material, while foil balloons, also known as mylar balloons, are made from a thin layer of plastic coated with a layer of metallic foil.
Latex helium balloons are more porous than foil balloons, which means helium escapes more quickly from latex balloons. On average, a latex balloon filled with helium will start to lose its lift after about 6 to 8 hours, while a foil helium balloon can stay afloat for several days or even weeks.
The Role of Temperature
Temperature also plays a crucial role in how long helium balloons last. Helium gas expands in hot weather and contracts in cold weather. So, if you leave your helium-filled balloons in a hot car or under the hot sun, the helium will expand, and the balloon may pop. On the other hand, cold temperatures can cause the helium to contract, making balloons in a cold room shrink and droop.
To maximize the float time of your helium balloons, it’s best to keep them in a room-temperature, air-conditioned room.