Tree Trunk Art Pottery Vase

Professional potter or student?
What caused the cracks?
Thanks

 

The cracks make me think student. Probably caused by improper handling of the clay before it was sculpted. Firing can reveal where the clay wasn't completely integrated. Even a small amount of air between 2 pieces of clay can show up when fired. I remember working clay in art class by repeatedly throwing it down on a table to get all the air out.

 

They left some vent holes on the inside but seems that was not enough.

 

Vent holes don't really help that kind of cracking. It is the result of air being trapped between 2 pieces of clay and not completely forced out. The clay was suppose to end up as one piece. Vent holes are for areas where the maker knows air was trapped