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".
One of the first things he did was to set up the "artisan section" of the bakery.
"Initially there were no croissants, no cookies, no (artisan section), there was only the main line," said Mr Leong, referring to the main production line that produces sandwich loaves. These make up most of the bread produced in the 990 sq m bakery and are largely consumed by inmates.
Now, a small section of about 10 inmates work daily in a small air-conditioned room, making tasty treats such as pineapple ingots, ciabatta bread and macarons. These are supplied to cafes, confectionaries and even airlines.
"Why did I decide to do this? If I don't create any new items, they won't learn anything," he said.
During festive seasons, the bakery sells directly to the public, said Mr Leong. For Chinese New Year, production has already started on an assortment of cookies.
Revenue from the bakery goes towards supporting efforts by the Singapore Corporation of Rehabilitative Enterprises to rehabilitate and reintegrate former offenders. Prisoners earn a token allowance while working at the bakery.
Most of the inmates have never baked before and it is a challenge for Mr Leong to explain the science of baking to them.
He teaches using bite-sized information, explaining how a baker needs water and sugar to "feed" the yeast, and then heat to push the gas out from the dough.
"You have to tell them bit-by-bit, like a story," he said.
He confessed that dealing with inmates was difficult at the start.
"Working here and working outside is different, you cannot (pull rank). You have to understand their characters to build a relationship," said Mr Leong, who talks to them mostly in Hokkien.
He has kept in touch with some former offenders who have passed through the bakery. One of those whom he is most proud of is Mr Jamal Yaacob, 50, a former security guard jailed for eight years from 2000 for drug-related offences. Mr Jamal started out at the main line packing bread, but asked to be transferred to the artisan section. Mr Leong said yes.
"I wanted to learn something in my time there," said Mr Jamal, who now supports his wife and four-year-old daughter on his monthly pay of $1,700 as a baker.
Mr Leong believes his humble craft holds important lessons for the prisoners. "The recipe for a decent life is the same for making good bread - hard work and no shortcuts," he said.