Melbourne-based sculptor Heather Swann took out the prize this year for her ink and wash on paper piece titled You are a balloon.

Her piece takes themes from the C.S Lewis book, Til' we have faces.

She said she had read the book when she was young and it had resonated with her.

The piece explores the fragility of human happiness.

"The balloon of happiness that we all have, we should be careful that it does not burst," Ms Swann said.

"It stuck with me for all of these years.

"I am not sure of myself.

"It's a very personal feeling of precariousness.

"I do realise when you make a work of art that many people will read things into it.

It is also quite gutsy and says something about who we are as humans.

The 52-year-old sculptor dabbles in drawing as a means to further develop her sculptures.

"Over the last few years I have become more confident about my drawings just as a drawing," she said.

"When I make a sculpture I do about 50 drawings.

"The drawings are sometimes really scrappy but this one developed."

Ms Swann said a new sculpture would soon develop out of the prize-winning drawing.

Ian Potter Museum of Art director and prize judge, Kelly Gellatly said the picture was deceptively simple.

She said Ms Swann's technique and skill was visible in the work.

She said the work was a balance between an abstract form and a person's figure.

"The words are also very deliberately included," she said.

"The way she works with the text makes it very visually appealing.

"It doesn't give any answers to what the work is about though."

Ms Gellatly said the decision was not an easy one.

She said the winning piece kept her thinking about it long after she saw it.

"You leave and it resonates with you and you continue to think about it," Ms Gellatly said.

The prize was initiated by former family court judge the Honourable Paul Guest QC.