Bloated

So I put the pieces from the last firing (which was a 1280 degree firing) in again and took them up to 1300 degree with a half an hour soak. In this I was hoping for more warping of the form, reflecting the forms I had accidentally got at the end of last year. These are the results.

Again, even taken up past vitrifying temperatures or any temperature that porcelain should normally go to, the forms themselves didn't really distort. However one unexpected occurrence did. Weird lumps appeared on the cup forms. Initially they look like someone has just poked the form from the inside whilst leather hard, but on closer inspection they are bubble in the form's wall.
Initially I thought these would be tiny bubbles of air that had got in to the clay body when mixing up my porcelain casting slip (you have to really mix the stuff up a lot to get it to become the viscosity for casting, and this can inevitably lead to bubbles getting in). However, when talking to Andrew (a guy on the MA ceramics course) he explained that it was most likely what is known as 'bloating'. This is when the clay has been taken past its limitations and gasses have formed from the actual clay body itself, causing the clay wall to push outwards.
I quite like how this imperfection looks, and may try and mimic it again.