Champagne clay

In the start of the semester I emptied the white smooth stoneware recycling container.  I knew it was a risk with all the yellow, brown and whoknowswhat lumps that were found in the bottom, but I anyway poured everything to the mixter. After the glaze firing of the test pieces I could see the clay had nice tone with spots but it is very bubbly. Specially the thrown cups have big bubbles which was disappointing, because I made the clay batch specially for the wheel. The pinched cup looks more even, but still you can see the same effect. I fired also some pieces for breaking to see if I could recognize what is causing it, but there was just air.
I thought first to throw all of the 60 kilos to trash but then I thought this clay might work well in sculptural work. So, I saved it and hopefully soon I will have time to make some big bubbly creature.