You still remember the sentences from the starting page?
(A kiln is simply a structure where heat is applied inside.  The source of this heat can be …)

The simplest kiln is a barrel where the greenware (unfired ceramics) and the fuel will be mixed putted inside.

The heat of the fire will be more homogenious and a bit more efficient (compared to a bonfire). But the firing process is still nealry without controll and therefore the cracks because of the heat stress will remain.