This use of Imperfective e to convey inchoative meaning is restricted to ‘adjectival’ items describing physical properties, dimension and colour. With adjectival items of other semantic types, such as human propensity (happy, ugly, etc), the verb kon is used to convey an inchoative sense. E.g.
A pikin e kon breiti.
[DET child IPFV come happy]
‘The child is becoming happy.’ (Winford 1997: 263)