How does gray pottery come into being?

A potter said: Gray pottery is specific to Iran and has not been seen anywhere else.
Mehrdad Mehrdadian stated: Gray pottery belongs to the second millennium BC, which was made on the plateau of Iran. In fact, because there were no metals at the time, this method of pottery was invented. This method of pottery seems to have originated through tribes such as the Aryans who entered the Iranian plateau.
He explained: The method of work is that the body of the pottery was placed in the kiln and after the baking process, smoke was prevented from escaping, and as a result, the carbon that was created penetrated into the body of the pottery and the pottery instead of They turn yellow or pea, turn black. The industry was new and popular at the time; But after the Iron Age, metals came into people’s lives and the gray pottery industry became obsolete.
He continued: Due to my personal interest, I went to this industry and I was curious to know how pottery looks like this. Although there was smoke in the kiln, the pottery did not turn black, so it was interesting to me that the pottery that was created was different from what had already been said. I worked on this type of pottery for about four years and got results. Of course, people like Dr. Nouri also reached gray pottery with their own special methods, such as furnace hole, but my method is different.
Regarding the reception of this type of handicraft, the potter said: When the pottery bodies are ready, I do a patina on it, which gives the pottery an old look, which makes it welcome.

