why do teabags swell up and get full of air when I’m pouring hot water onto them?
In: 295
The air is already in the bag mostly. It’s being displaced as the tea leaf sucks up water. The space between individual particles of tea leaf is a lot of air. That air has to go somewhere as the leaves slurp up moisture. To some degree it’s possible you’re trapping a little steam depending on how hot your water is.
The air that’s already inside the bag expands when it’s heated up by the hot water you pour on it
The water on the top of the bag makes a bubble. Then the air between the leaves is forced to the top as the leaves get wet. The water isnt sealed in but it also can’t easily get out so it floats until you squish it
Air easily passes through dry fabric (or paper), but once it’s wet, the water’s surface tension prevents air from passing through it. So, a wet tea bag is (somewhat) airtight. If the tea bag gets wet while it has air in it, the air can’t get out. And the air expands as it gets heated by the hot water.
Whereas if you lower the tea bag gently into water, the air escapes from the top of the bag which remains dry until the entire bag is submerged in water.
The tea bag senses danger and puffs up to protect itself from the impending threat. /s
It’s just the air already in the bag expanding now that it’s been rapidly heated by the water.
I used to get annoyed by this too. It’s all in the way the water is poured in.
Pour the boiling water into the mug or pot so that it wets the bottom of the tea bag/s first. The teabag needs to up off the bottom of the cup. I hold the teabag up by putting the tag under the bottom edge of the mug.
Continue pouring *slowly* so the water is flowing over the bottom of the tea bag. By the time the mug is full the bag will be saturated and won’t puff up with air.
tl;dr – Pouring the water over the teabag makes it air tight, but liquid can still flow in and out. The plant matter has tiny amounts of air inside of it, and it will come out as it rehydrates. The hot water has gas dissolved in it, usually, and it can also get into but not out of the bag.
The way you pour/dip the bag into the water. Yes. This can cause it. If you just pour the water in fast, then it can ‘trap’ a bubble of air inside the now moist bag. Same as your shorts when you go in the pool. However, if you dip slowly and carefully and let the water soak into the bag… It still has a bubble of air in it after a few minutes. So it has to be inside the actual plant matter.
The plant matter is dried, and it contains pockets of air where water used to be before it was dried, and it expands as it is warmed up by the hot water. So even if you are perfect with the dipping technique, you can’t get all of the air out from the plant matter. The bag itself will become wet and seal in that air, long before it has time to expand and escape the plant material.
And the last one is that the hot water is usually boiled pretty recently, and as such might have a lot of dissolved gas inside of it. Unlike carbonation, where it is forced into the liquid, this is far less total volume of gas. Just enough to stick to plant material and/or the bag. The outside of the bag can shed off bubbles, but the inside of the bag is going to have tiny amounts of dissolved gas slip through, and then find a place on the plant matter inside to become a bubble. Tiny, tiny amounts of gas. But it is enough.
[removed]
It’s not hot air, the tea is screaming due to being boiled alive.
You are a monster.
/s
Latest Answers