My art belongs to daddy

Lucian Freud's sculptor daughter, Jane McAdam Freud, has made a gigantic earthstone triptych sculpture of her late father's head, to help "keep him alive". Made in terracotta and measuring 3ft x 3ft x 1ft, the giant relief only came out of the kiln last week. "I can't put in words how it helped me with the grieving process," she says. "I was keeping him alive in a metaphorical sense – he was there the whole time I was making it."

The sculpture, which has taken up an enormous chunk of her studio at home in north-west London, will be leaving next week to be unveiled at London's Freud Museum on Wednesday – the former residence of her great-grandfather Sigmund Freud.

"Home is not very far from the museum," says McAdam Freud, with some sadness in her voice. "I know it will be in safe hands."

Estranged from her painter father at the age of eight, the making of his giant head has special pertinence. The two were only reunited 23 years later, when at the age of 31, she spent many hours with her father just before his death in July 2011. She made sketches for this new work as he lay dying in bed at home. "I needed to stare at him for hours. I showed photos of the big head to him. Then it was just an enormous slab of clay with no specific features. My husband, Peter [Henson, an architect], kept asking me, 'Who is it?' I knew it was going to be my father. My father knew it too; he raised his eyebrows because it was a big job I had in front of me," she recalls. "I had to get the nose right – it changed in its profile – it was such a distinguished, shapely nose."

The sculpture, entitled EarthStone Triptych, will be exhibited for the first time in the exhibition, "Lucian Freud, My Father", in Sigmund Freud's former dining room at the museum. Her great-grandfather had the quirky habit of bringing his new acquisitions of ancient sculptures to the dining-room table, during meals, as a "guest of honour". Now, the arrival of Sigmund's grandson taking "the place of the guest of honour" shows its special significance.

As McAdam Freud drew in the eyes, nose and mouth and started modelling the nostrils on her father's face – this three-dimensional relief works in the round – it helped her to come to terms with his imminent death.

"I was feeling those feelings one has on the impending death of a father. I had previously consciously avoided using his image all my life – focusing more on Sigmund – but I had to face my father," she says. "I had to face the fact he was dying. In the end, I made it into a triptych because I think he had many sides."

McAdam Freud recalls her father lavishing attention on her whenever she was drawing or painting as a child. "He used to watch me painting and drawing on the back of these plywood orange crate lids. That's when he gave me the most attention. I remember thinking he was a constant in my life." But her mother, Katherine McAdam, moved the family away from their father when McAdam Freud was eight, leaving no forwarding address. "That relationship was severed and that was so upsetting."

When she reunited with her father, they sat for each other when he asked her how to model in wax. "He said, 'Jane, work in various scales. Don't work in one scale. Work on the intimate and the large scale.' I'd only ever worked on an intimate level. This encouragement changed my whole working outlook. I found I could express myself so much more."

The contemplation of his death also led to the imagery of other sculptural works DuoHead and Moses and Mary, but they were not created directly from him sitting for her. "I knew he liked my work because he gave me a backhanded compliment," she recalls. "I wanted to make medals of him. But he thought it would be vain. So he said, 'Let's do it later.' I explained it would be more of a memento mori. I said, 'Can I do it now?' He said, 'No, it will become public because good work becomes known. We can't keep it between us.'"

Now, the two handheld medals of her late father from the sketches will go on show, alongside this earthstone triptych. The table is being removed from the dining room at the museum where her grandfather ate – to allow the giant head its own place, in front of a mirror for a good view. Visitors can also perch on a little stool and meditate over the middle head. "The middle head looks stern and a little bit like a cobra if you squint," says McAdam Freud. She describes the snake's significance "as a metaphor for protection on some level".

It took her 10 months to finish the earthstone head – and now she must let it go as it travels the UK, next stopping at London's Gazelli Art House, in Mayfair, for her solo show in April.

Luckily, the rest of her family are delighted with the finished result. "My sister Lucy said it should be outside the National Portrait Gallery," she says. "Dad has one eye open and one eye closed. When you are drawing it is a way of measuring – so this portrait could be him working, close to death, dreaming or asleep, or all of these things."

Lucian Freud My Father, Freud Museum, London NW3 (www.freud. org.uk) 25 January to 4 March