About a year ago we were using a white clay with grog. The grog was good for stability when hand building, but when wheel throwing it was less pliable. Most pieces when glazed were bright in color, but the work just didn't speak to us.
After some research we decided to try the Standard 112 brown speckle clay which is known to have warm earth tones and looks beautiful with just a clear glaze. After the first firing, we knew that this was the look we were wanting, but there was just one major problem. All of the pieces after the glaze firing were bubbling. We thought, what did we do different? So we tried again with another batch of bisque firing then glaze firing and had the same results. So much time wasted, about 2 months of work lost.
Through lots of reading, conversations in chat rooms and support through friends on social medias we found out that we needed to slow down our bisquing process to allow for more of the material to burn off before vitrifying the clay.
We loaded up the kiln for the third bisque firing using the new clay and adapted our firing schedule to hold between 900 degrees celsius and 1000 degrees celsius for 2 hours. Not knowing if it worked or not, we still had to glaze everything and fire the kiln once again. The third bisque firing was a success!