Patina,
hmm, if your pot is porous, glaze does not fit the body,glass glaze is unbalanced, all of these can allow for chemical reactions.
Well fired stoneware is impervious to many substances, especially water, and it would take a very, very long time to affect a real surface change, same for a well balanced glaze, even on earthenware that is still porous as the body goes.
[ There is also earthenware that has been rendered non-porous.]
On netsuke of wood or ivory, and Yi-Xing teapots, the porous body allows for absorption, from oils, hand or walnut oil, and tea being constantly drawn at 90 dge.C.
Patina on well fired stable pottery bodies, would probably be just something organic, growing on it.
Personally, I would just buy a better grade of pottery, where the shape, colour and anything else, pleases my eyes and fingers.
Al, I have a few of those Roman rings, buried by soldiers going off to war and dying before they could dig back up their property. They are genuine because the Ebay site said so.
Anyhow, it was not my intention to offend, just get everyone thinking about this Patina thingee.
By the way there is a site on-line that teaches you how to patina, your pottery.
I just received two pots from somewhere in rural China land, they have to have the drainage holes put in. BUT like some of the teapots, from Ebay, they have patina - wax jobs - ha ha ha.
The teapots were done with shoe wax, black shoe wax. I had to boil them to clean off the crap.
Why did I purchase.
Because I liked the shapes and I was taught to purchase [ if I could afford ] what I like, and not the nonsense many folk get into.
"Wow, it's an antique, and I can have to show off, even mention the price [ or as they do it on Ebay, this item is over 25 years old ------- it's Vintage - ha ha ha ]"
Always get some form of genuine, approved documentation, when buying an antique.
Or you may find that you are stuck with junk, and no re-sale if you get into a bind.
Or you may find your children trying to dump the stuff when you die [ see Neli's post on Bonsai brought to her school for sale by a man's son, if you need an example.]
Wishing you all well.
Good Morning
Anthony
* one day we can discuss resale problems with hobby items on the whole.
Example of genunine Egyptian Fiaience