What is wrong with this pot?

[DirtyCoconuts]

smart people are often wrong....we just learn from it

and even better....learn from the mistakes of others, you wont live long enough to make them all yourself

[JScott]

Originally Posted by DirtyCoconuts

smart people are often wrong....we just learn from it

and even better....learn from the mistakes of others, you wont live long enough to make them all yourself

Well said.

[SouthPark]

Somebody here was talking about a terracotta pot for fish. How to use Terra Cotta Pots in Your Aquarium

[Fairorchids]

Originally Posted by Ray

As the Orchid Board's resident ceramic engineer, I can tell you it all has to do with the firing cycle.

The oxidation state of the iron oxide in the clay can change color depending upon the firing atmosphere, turning red, black, and green (think Coca-Cola bottles).

With excess fuel (likely natural gas) poured into the kiln, it is reduced and a black color. After the flame is extinguished and the clay is allowed to cool (slowly, to prevent cracking) the fuel-lean atmosphere is oxidizing. As the oxygen penetrates the porous clay body, it turns "orange" from the outside in.

Apparently, in the case of that pot, the entire thing cooled enough that the iron wasn't thermally energetic enough to fully oxidize in the interior.

I use a lot of clay pots, and regularly break some**. Most pots are made in Italy, and they all show this color pattern (indicating a shortened cooling cycle, in order to speed up production time).

** I drill holes for wire hangers in many pots, occastionally breaking some (not to mention Cattleyas with roots everywhere on the outside of the pot, forcing me to break the pot deliberately).

[Ray]

Different folks have knacks, or maybe just interest in different things.

My wife was smart enough to be on Jeopardy (aired Thanksgiving day, 1990) but I wouldn’t even try. However, if they ever held “Family Jeopardy”, we might clean up, as between our two kids and us, we cover a broad range!

[WaterWitchin]

“I am wiser than this man, for neither of us appears to know anything great and good; but he fancies he knows something, although he knows nothing; whereas I, as I do not know anything, so I do not fancy I do. In this trifling particular, then, I appear to be wiser than he, because I do not fancy I know what I do not know.” ~ Socrates

It is a steep learning curve, requiring patience. At times it requires you to admit you don’t know as much as you thought you did. ~ WaterWitchin

[DirtyCoconuts]

FAMILY JEOPARDY would be a blood fight haha
id watch and want to participate

[Ray]

Another aspect of "wisdom" is realizing that the more one knows, the more you realize how much you don't know!

[SouthPark]

Originally Posted by LittleBigOwl

others suggested that this is just some sort of unfired clay that is inside (but why is it black?)

It is a good question, especially because the thick cross-section is black-coloured, while the thin cross-section region is gray/grey-coloured (or mostly grey-coloured).

[Ray]

Originally Posted by SouthPark

It is a good question, especially because the thick cross-section is black-coloured, while the thin cross-section region is gray/grey-coloured (or mostly grey-coloured).

Did you not understand my explanation of the iron oxidation state and how the processing can affect that?

The flooding of fuel into the kiln (known as "flashing") is intentionally done in brickmaking to result in a non-uniform surface appearance.