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What happens if you put anything wet in that bowl? Doesn’t it need to be glazed? And how could you glaze it at home?

silves89 2y ago
The raw clay wouldn't be vitrified, so it would be porous and would seep or leak. A glaze is a glass, more or less, and to get the silica to melt you need a flux. There are different fluxes for different temperature firings, but suddenly things are getting a little more precise. Without substantially levelling up the kiln tech and design you'll be at best low-fired and probably using lead as a flux. E.g. terracotta and earthernware. Early peoples would have used wax or fats to seal pots like these, to make them functional. People do that with modern pit-fired pots too, or use other sealants. I designed and built my own high-fire kiln, but it uses industrially made light-weight insulating and refractory brick, and gas burners, and I use Orton cones to know when I've hit the right amount of heat-work, and a pyrometer to take temperature readings. But some brave souls make their own bricks, and look at the colour inside the kiln to know when they're at temperature.
- Neil44 2y ago
  I used to use an electric kiln to do firings for my partner. It was fun working on the process. Our house had a lowish supply voltage so I ran 10mm2 cable back to the consumer unit, and experimented with the impedance of the elements, as we did a lot of quite high firings. I used an electronic kiln controller mostly but occasionally verified it against an Orton cone. Gas would have been more economical but a bit more scary, for me anyway.
  - silves89 2y ago
    It's scary for me too! And way less economical in the UK than electric. My small electric kiln costs £5 to fire. My big (perhaps 4 times the size) gas kiln costs £70-£80. I'd much prefer firing with wood. But I'm too suburban and firing with wood takes much more effort in prep and during firing, but it's a pleasant and exciting experience! Which gas firing is not.
itronitron 2y ago
You could put a lot of bones and some salt in there, most of the minerals will vaporize and deposit on the clay as a glaze.

The raw clay wouldn't be vitrified, so it would be porous and would seep or leak. A glaze is a glass, more or less, and to get the silica to melt you need a flux. There are different fluxes for different temperature firings, but suddenly things are getting a little more precise. Without substantially levelling up the kiln tech and design you'll be at best low-fired and probably using lead as a flux. E.g. terracotta and earthernware. Early peoples would have used wax or fats to seal pots like these, to make them functional. People do that with modern pit-fired pots too, or use other sealants. I designed and built my own high-fire kiln, but it uses industrially made light-weight insulating and refractory brick, and gas burners, and I use Orton cones to know when I've hit the right amount of heat-work, and a pyrometer to take temperature readings. But some brave souls make their own bricks, and look at the colour inside the kiln to know when they're at temperature.

Neil44 2y ago
I used to use an electric kiln to do firings for my partner. It was fun working on the process. Our house had a lowish supply voltage so I ran 10mm2 cable back to the consumer unit, and experimented with the impedance of the elements, as we did a lot of quite high firings. I used an electronic kiln controller mostly but occasionally verified it against an Orton cone. Gas would have been more economical but a bit more scary, for me anyway.
- silves89 2y ago
  It's scary for me too! And way less economical in the UK than electric. My small electric kiln costs £5 to fire. My big (perhaps 4 times the size) gas kiln costs £70-£80. I'd much prefer firing with wood. But I'm too suburban and firing with wood takes much more effort in prep and during firing, but it's a pleasant and exciting experience! Which gas firing is not.

itronitron 2y ago

You could put a lot of bones and some salt in there, most of the minerals will vaporize and deposit on the clay as a glaze.