About The Bonsai Pots & Pottery
The Stoneware Pots I make are fired in a kiln to approximately 2300 degrees Fahrenheit.
Most Stoneware, like Porcelain, is completely non-porous when fired and will not absorb water. Stoneware is more rustic looking than fine Porcelain, and is fired close to the same temperatures as some Porcelains. I fire my Porcelain to 2300 degrees Fahrenheit, also, and they will be completely non-porous when fired and will not absorb water.
Pots that are fired at these higher temperatures will be more able to 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 take freeze-thaw conditions, you can try setting your dry pot into a bucket of water. All unglazed pottery surfaces will lightly bubble for a moment due to the air trapped in the rough texture of the clay, if it fizzes and bubbles like a carbonated soft drink, than it would be too porous to leave outdoors in winter.
My brown stoneware is extremely hardy. I used this clay to make a large outdoor food bowl for my dog many years ago, it has been outside in the 100 plus degree heat in the summers and extreme minus 30 degree snow and cold, in the winter. It has outlasted my beloved dogs, my Rottweiler, my Great Pyrenees, and is now currently being used and played with by a Maremma livestock guard dog.
The Earthenware pots I make are formed from different clays and fired to lower temperatures leaving them lighter in weight, more porous and able to absorb water. The Terra Cotta Pots are fired to earthenware temperatures and will absorb the most water, if left unglazed. Glazed Earthenware pots are sealed and will not absorb very much water. Unglazed Earthenware and Terra Cotta Pots should not be left outdoors in extreme climates, due to freeze thaw conditions that will eventually break down the pot.
All of my glazes are lead free.