How do clay teapots/plates and clay pans work, how does the the tea/liquid not soften it up or make it all clumpy? And how does the heat not make it burn or catch fire?
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Clay is fired in a kiln, the clay undergoes chemical changes when exposed to high heat. The Kiln doesn’t just dry the clay out, some of the large particles in the clay melt and fuse together. The process makes pottery waterproof.
So a few things, when making pottery it is coated before put into the kiln(pretty much an oven) ensuring all and any open pores are sealed. Also even before the coating, it’s all about the quality of the clay and dedication that went into it and making it near perfect.
The heat expands and solidifies both the clay and the coating making it so that nothing seeps through. So now you have a substance that is pretty much solid all the way around.
Heat does affect it, however to actually get it to the point of melting or whatever is beyond the normal temperatures that it’s being subjected to. Obviously if you’re rapidly heating it up and cooling the pot or cup of anything really, it will break. However that’s with anything, especially glass, some take more heat and more times for this to happen.
Ceramics aren’t just made of dried clay. They’re heating to extremely high temperatures (several thousand degrees) in a kiln. This doesn’t just dry out the clay, it actually permanently changes the crystalline structure of the clay to make it hard. This process can’t be reversed. Think of when you paint a wall in a house. Once the paint is dry, you can’t make it wet again by getting the wall wet, right?
So the kiln firing process permanently hardens the clay and changes its crystalline structure so that it become permanently hard.
Hot liquids can’t melt ceramics or set them on fire because, again, once they’ve been through the kiln, their structure is changes so that they become vitrified, with glasslike properties. They have extremely high melting temperatures – far higher than boiling water. The only way melt a ceramic is to put it back in a kiln and heat it up to several thousand degrees.
We also coat ceramics in a glaze. When we put the ceramic piece in the kiln, the glaze gets so hot it partially melts and essentially turns into a thin, impermeable glass layer.
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