STEPPING into the bakery at Changi Prison's A3 cluster, a great roar greets you.
It is a mechanical medley, from the hum of the truck-sized oven that churns out more than 1,500 loaves an hour, to the whirring mixers which knead the dough into shape.
Working with this metallic orchestra to turn 3,500kg of flour into 10,000 loaves a day are 120 inmates, each dressed in the white cotton garb of a prison baker. Watching over it all is Mr Kenny Leong, master baker and mentor.
"The first thing I tell them, this work is tiring, if you work for 10 hours; you'll stand for 10 hours. But if you develop a passion for it, you will like it," said the 50-year-old.
Fights and quarrels are minimal, says Mr Leong. His "staff", as he calls them, are well trained - apart from an occasional word of guidance, they work quietly.
Mr Leong, a baker since he was 20, used to be with a major bakery chain. He joined the bakery inside the prison six months after it moved to Changi Prison from Moon Crescent Prison in mid- 2004. "A friend approached me and asked me to come and have a look.
If people didn't tell me, who would know there's a bakery here?" said the father of 18-year-old twin daughters.
At the time, the bakery lacked a professional baker to oversee its operations, said Mr Leong.
But he admitted he had doubts at first. "In the initial stage when you come here, a normal person would think, these are inmates. All the offenders and rapists, so many down here, how am I going to work with them?" he said.
But he decided to take the job "to give himself a challenge".