What is the significance of the absence of the face in the artwork?

It creates a brooding and sad expression

Answer: It creates a brooding and sad expression
The absence of the face in the depiction of the woman gives the artwork a brooding and sad expression.

Of Walls is an etching made from zinc plate and printed on paper made by Anupam Sud in 1982. She had studied printmaking at the Slade School of Fine Art, University College, London, in the early 1970s. When she returned to India, she was drawn to its everyday reality. Apart from her deep interest in social problems faced by people, belonging to marginalised communities of the society, she was keen to understand them artistically. Notice how she creates an interesting form of a woman by hollowing out the face. The absence of face gives it a brooding and sad expression. The painting depicts the figure of a lonely woman seated on the pavement before a dilapidated wall. In the foreground, we only get a glimpse of the lower part of a poor man sleeping on the ground, contrasting with the clothed woman, and adds to the sadness of the print.