I just know that stoneware dishes that I have hand made and fired ( wedging the air out of the clay extremely well) do not ever have this problem, but the light weight, aerated slip cast stuff from mass market stores often does. It cuts across all colors and types of glazes. It really very much seems to be the density of the clay the vessel is made from, which is just another way to say, how aerated it is. The same thing is also observable when it is a dish I have hand made and fired from porcelain, which is why I’ve assumed it is technique/physical construction and not the actual clay or glaze type. Perhaps instead it is the amount of total vitrification of the clay, which would also affect the density of the finished vessel as well.
I just know that stoneware dishes that I have hand made and fired ( wedging the air out of the clay extremely well) do not ever have this problem, but the light weight, aerated slip cast stuff from mass market stores often does. It cuts across all colors and types of glazes. It really very much seems to be the density of the clay the vessel is made from, which is just another way to say, how aerated it is. The same thing is also observable when it is a dish I have hand made and fired from porcelain, which is why I’ve assumed it is technique/physical construction and not the actual clay or glaze type. Perhaps instead it is the amount of total vitrification of the clay, which would also affect the density of the finished vessel as well.