I have one balloon here which has shrunk in size, and another - equally old - which is hardly shrunken at all. Is the deflation of the balloon all down to leakage of air through the balloon’s skin? Or is it due to a not-quite-tight enough knot? Does it make a lot of difference if there’s a differenct in temperature between the air inside and the atmospeher the balooon is in? And does the fact the air I’ve blown in contains carbon dioxide, or is slightly moist, make a big difference?
What’s the best technique to keep a ballon fully inflated for as long as possible?
Thanks in advance for answers to these many questions!
When you buy helium balloons at the balloon store, they ask if you want them ‘coated’. I don’t know what the substance is, but they squirt something that looks like hand sanitizer into the balloon before they blow it up. It makes the difference between the balloons lasting a day and lasting a week.
The difference in material is surely causing the different deflation rates you’re noticing. Even different colored balloons made of the same material can have different properties. Anyone ever get a bag of water balloons and have every pink (or yellow, etc) balloon break when you try to attach it to the spigot, yet not have any problems with the other colors?
It’s the porosity of the material, and sometimes a bad knot. Temperature differences will equalize over time, but if the ballon is moved into lower pressure ambient air, the pressure difference would increase the rate of leakage. Mylar has very low porosity, especially when coated with aluminum, and materials can also be coated with other agents to help prevent leakage. Thicker balloon material usually leaks less. Helium balloons deflate faster than those inflated with just air because helium atoms are very small, and very inert, so they fit through the tiniest spaces without sticking to anything or clumping up.
The difference in your two balloons may be differences in the material, or just a small hole in one balloon that allows air to leak out faster. Elastic balloons will increase in porosity as the internal pressure increases and the material gets thinner, and pores increase in size. That can result in balloons that deflate rapidly initially, and then much more slowly after the pressure decreases. The best way to keep a balloon from deflating would be to keep it in an enviroment of higher pressure than inside the ballon. Of course that will actually inflate the ballon as the leakage goes the other way. And it’s not much of a balloon in that state either. Edit: Xema already recommended that.
As others have stated, the gas in a latex balloon leaks out through the pores in the balloon’s skin.
The rate of leakage does indeed depend on the type of gas, dictated by Graham’s Law of Effusion. Graham’s Law states that the rate of effusion of a gas through a small hole is inversely proportional to the square root of the mass of its particles. Therefore, helium gas will leak out faster than air (which is a mixture of nitrogen, oxygen, and various other smaller constituents, including carbon dioxide).
Heh - as I was writing that word I remember thinking “hmm, doesn’t seem right” but for some reason I settled for my best guess rather than looking it up!
The well-inflated ballon was also kept in a darker place in the same room as the deflated balloon which is on top of a desk near the window (ref to Xema’s post about light affecting the material), though I wonder if that could have made such a difference especially as the balloons are made from slightly different materials. I’ll vote for a combination of the two. Thanks again all.
