"Nothing great comes out of prison. It's a place of hopelessness," he says.

"Art calmed me down and gave me a focus, because I was fairly lost.

"When I first started I was doing pretty dark work. The teacher directed me to lighten up a bit and do lighter work."

The 36-year-old now works full time as an artist in Newcastle and says his teacher and art classes in prison turned his life around.

"It gave me some self belief that I could be an artist. Now I'm confident to produce commercial work that will sell," he said.

Farrell's seven-year jail sentence, for drug trafficking offences when he was in the army, was reduced on appeal and he was released two years ago.

Unions across NSW including the NSW Teachers Federation are rallying against the Baird government's plans to privatise the work of prison teachers. Unions say the teachers have helped rehabilitate prisoners and reduce reoffending.

The state government expects to save $5 million a year by cutting the number of fully trained teachers from around 158 to 138. About 20 teachers will remain and education programs will be delivered by an external training organisation.

Unions NSW secretary Mark Morey said lowering education standards would not help prisoners turn their lives around.

"It's likely to channel them back into antisocial and unlawful behaviour," he said.

"High-quality education is essential for prisoners to develop the knowledge, skills and motivation to gain employment, making them less likely to offend."

Unions have protested outside Parliament House in Sydney and have collected around 12,000 signatures against the planned changes.

Daniel Conlon, 50, who works as a teacher at Long Bay Correctional Centre in Matraville is among teachers at risk of losing their jobs at the end of this year.

Mr Conlon said teachers could apply for 20 remaining teaching positions or a downgraded training clerk position.

"Education qualifications won't be needed for that new job," he said.

"You need to build up trust with the inmates and over time you persuade them of the benefits of education.

"Other operators won't be experienced in the way of jail. I can't see how it will work."

A former university lecturer, Mr Conlon said he and other teachers were passionate about teaching in prisons where education programs range from basic literacy and numeracy to year 10, HSC and higher education qualifications.

"It's a fantastic job," he said.

"The people I deal with come from dysfunctional backgrounds, with a negative view of life and the benefits education can bring.

"It takes time to get people to trust you and have a positive attitude.

"I've had students who have become engineers, teachers."

The Minister for Corrections David Elliott said the new prison education model will more than double the number of inmates completing literacy and numeracy courses to 1840 per year. He said the number of inmates doing vocational education and training activities would increase by 20 per cent

Cost savings would be redirected into programs to reduce reoffending.

"A review of the current education model concluded that it does not meet demand," he said.

"Corrective Services teachers currently accrue 11 weeks leave per year. Of the hours that were potentially available for teaching in 2015, only 62 per cent were used.

"There have been negotiations with the Teachers Federation to increase teaching weeks by teachers staggering their leave. Regardless of the way leave is scheduled, the full teaching load cannot be delivered."

Mid North Coast, Lithgow, South Coast and Wellington correctional centres will continue to be staffed by 20 teachers.

About 70 new prison-based jobs will be created to match prisoners to training programs.