Most potters fire their pots twice: For stoneware, the first (bisque or biscuit) firing is to around 950-1000 Celsius and results in hard, but still slightly porous pots. These pots are easy to handle and strong. They are then glazed and fired again - usually to around 1220-1260 Celsius for pots similar to mine.
Unfortunately the glazes used in this process, often don't work on 'raw' pots, that have not been bisque fired first. The glaze either shrinks away form the pot or cracks, or does other equally disastrous things! It has taken me an age to adapt my glaze, first making it more suitable to 'fit' the raw clay, and then adjusting the chemicals (silica in particular) to compensate for the increase in shine caused by the first adjustment The actual glazing process is also more tricky, as the dried clay pots are so much more fragile than the once fired pots. If a 'raw' mug is dropped in a bucket of glaze, it will quickly dissolve into a sludgy heap.
Having said all of that, it is all achievable and some potters have always worked in this way. It is not only cheaper, but more time-efficient and most importantly for me, reduces my environmental impact. I am so pleased that I have been able to start adopting the raw glazing method, and will soon be producing more of my pots this way.