a) in the first step of polymer gelling into a surface gel skin, just after immersion in the water coagulation bath ;
b) seconds later, in the next step of gel domain formation in the sub – gel skin layer ;
c) in the step of formation of a surface crater by solvent ejection under gel collapse pressure through weak points in the gel skin, followed by a self- sealing of gel skin at the break point ;
d) in the step of formation of a macrovoid by water- rich solvent flow towards the bottom face under gel collapse pressure, and subsequent preferential phase separation and gel domain formation on the flow path.
