About the Pots and Building Process At White Horse Pottery
The Stoneware pots I make are fired to approximately 2300 degrees Fahrenheit.
Most Stoneware, like Porcelain, is completely non-pourous when fired, and will not absorb water. Stoneware is more rustic looking than fine Porcelain, and is fired close to the same tempuratures as some Porcelains. I fire my Porcelain to 2300 degrees F also, and they will be completely non-pourous and will not absorb water.
Non-Pourous pots fired at these high tempuratures will withstand freeze thaw conditions. If your pot is frozen to something do not try to remove it until it is thawed.
To test your pot to see whether it can withstand freeze thaw conditions, you can try setting your dry pot into a bucket of water. All unglazed pottery surfaces will lightly bubble for a minute due to trapped air in the rough texture of the clay surface. If it fizzes and bubbles like a carbonated soft drink, than it would be too pourous to leave outdoors in winter.
My brown stoneware is extremely hardy. I have used this clay to make a large outdoor dog food bowl for my dog many years ago, it has been outside in the 100 degree plus heat that we get in the summers, and minus 30 degree snow and cold we get in the winters. It has outlasted my beloved dogs, a Rottweiler mix, a Great Pyrenees, and is now currently being used and mauled by a Maremma live stock guard dog.
My Earthenware pots, are made from different clays and are fired to lower tempuratures, leaving them lighter in weight and more pourous and able to absorb water unless completely glazed. Terra Cotta Pots are fired to Earthenware tempuratures, and will absorb the most water if unglazed completely. Unglazed low fired pots should not be left in the outdoors in winter, due to the freeze thaw conditions that will eventually break them down.