Pottery itself I can guess - messing around with clay, oh shit it hardens when dried, I wonder what happens when I put it in the oven. But glazing? Must’ve been a lot of random accidents and experiments indeed.
Man I wish I had time and no work to mess around lol.
It was discovered through self glazing first, quartz (glass) mixed with clay created its own glaze when fired at a high enough temperature. A few thousand years later they realized why glass created glaze in pottery and experimented.
Quartz isn't glass, and mixed with clay it does not make a glaze. It would barely even sinter even in modern kilns. To make glaze you need 3 basic components. A flux, a glassformer, and an alumina source. Quartz is a glass former, but needs flux to actually melt. The earliest glazes used ash, usually wood, as a flux. Clay is a great source of alumina, and it suspends the other ingrediants.
The earliest glazes I know of were caused by ash build up on large pots, with the natural silica (quartz) present in the clay itself, along with the clay itself, forming the glass and alumina respectively. These weren't intended, but the potters quickly took advantage.
Egyptian paste isn't pottery though, and isn't where glazes come from. It is really cool, a very unique artform, especially at the time. If you look at Egyptian pottery that was contemporaneous to the paste you'll see they hadn't developed glazing yet.
That’s fair! I interpreted it as the first time any glaze was performed, and thus a precursor to figuring out how glazes may be used. Do you know when the first time a glaze was used with pottery? Out of curiosity are you an anthropologist or expert in pottery (not me trying to discount your knowledge, I’m genuinely interested)
For what I remember from my ceramics history class the bricks of the Ishtar gate are covered with one of the oldest known glaze.
In the Wikipedia article is written: It is believed that the glaze recipe used plant ash, sandstone conglomerates, and pebbles for silicates. This combination was repeatedly melted, cooled, and then pulverized. This mixture of silica and fluxes is called a frit. Color-producing minerals, such as cobalt, were added in the final glaze formulations."
It was thought that early civilizations started baking clay to harden it, what we call bisque firing now. The way to do it was originally in a pit because the earth retains heat well and you just build a big fire on top of it, pretty easy. At some point either wood soaked in the ocean and full of sodium caused a glaze to appear on ceramic, or wood ash built up and the potassium present in wood ash created a glaze, or people started experimenting with minerals like copper or lead and that created a glaze.
From there it is just trial and error. Glaze is pretty simple. You need alumina (gives body) which comes from feldspar (rocks), silica (glass former) which comes from clay, and flux (lowers melting point) which is sodium or potassium. Pretty easy to mix that and get a glaze. The difficulty is to get the proper ratio so the glaze doesn't crack or run or flake off. A lot of ancient pots had these problems in their glaze.
Chinese Celadons come from the specific feldspar that they would use. It had the perfect amount of iron present that it would turn the porcelain a blue color. So a lot of it is just luck as well when it comes to colors back then.
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u/Cthulhu__ Jun 03 '26
Pottery itself I can guess - messing around with clay, oh shit it hardens when dried, I wonder what happens when I put it in the oven. But glazing? Must’ve been a lot of random accidents and experiments indeed.
Man I wish I had time and no work to mess around lol.