Temp of ceramic blanket surface?

[MaineLotus]

Constructing an indoor 32" oven. Planning on 3" of ceramic blanket. What can I expect to see for temperatures on the outside of the ceramic blanket?

[CoyoteVB]

Re: Temp of ceramic blanket surface?

I have 4" of ceramic blanket and the outside of my dome (scratch coat of Stucco) is ambient temperature. I fired the oven 2 days in a row and the temperature on the outside did rise a little. The surrounding surfaces were about 40 degrees and the top of my dome was 62 degrees.

[brickie in oz]

Re: Temp of ceramic blanket surface?

Ive clocked the inside of my oven at 600c after a long burn so I would imagine the outer skin of the bricks would be the same.
I can get a probe onto the outer side of the CB and it clocked 50c with 30mm of CB.

[david s]

Re: Temp of ceramic blanket surface?

Ive clocked the inside of my oven at 600c after a long burn so I would imagine the outer skin of the bricks would be the same.
I can get a probe onto the outer side of the CB and it clocked 50c with 30mm of CB.

The surface of the inside might read 600C, but the inside of the brick will be nowhere near that and the outside of the brick, where the ceramic fibre contacts it will be much lower again. IR thermometers are notoriously misleading for this reason. If the surface of your brick reads 600 C, depending how long you've been firing, then the outer surface will be in the region of 400 C. When removing the spyhole plug from kilns there is usually a drop of around 100 C per inch.(using a dense clay plug) This varies of course depending on the insulating qualities of the refractory used.

[Laurentius]

Re: Temp of ceramic blanket surface?

Hi David,

So you're saying that a fully saturated brick is never fully or uniformly saturated, regardless of the amount of heat applied or duration of the application?

[david s]

Re: Temp of ceramic blanket surface?

No. Not while you are firing. Give it an hour to rest and the heat will equalize more, depending how thick your walls are. Folk who have installed thermocouples at the outer surface of their inner brick walls would probably confer. Clay bricks are actually more insulating than conductive. Take a look at the thermal conductivity of different materials. For a typical firing of around one and a half hours with normal thickness walls (3-4 inches) there will be a considerable difference in inner and outer brick temps. Fire for five hours and readings will be closer.