Watch: Removal of Mark Cropp's 'Devast8' tattoo begins - but 'prison ink' making it difficult to take off

The tattooist removing Mark Cropp's distinctive 'Devast8' facial tattoo says it may be difficult to remove because the ink was made from unusual ingredients in prison.

Mr Cropp says he has had trouble finding work since being released from jail due to the tattoo, which he got inside after a night of drinking home-brewed alcohol.

He has appealed for work, which has led Sacred Tattoo to offer to remove the tattoo for free - but co-owner Briar Neville told the NZ Herald the unusual ink it was done with could prove a problem.

"The ink that he's used is not your regular ink - it's something that they've made in prison by melting down plastic utensils," Ms Neville said.

"Essentially, that created soot, which is carbon ... tattoo pigments are made from carbon - the black inks - but it's hard to know what to expect once we start lasering."

She said it was the largest facial tattoo she had ever worked on and it's estimated that removal could involved between eight and twelve sessions.

"We'll probably get him back in a week and see how the skin's behaved and what the tattoo's doing and decide whether or not we're going to go ahead and do the whole thing."

Mr Cropp was convicted of aggravated robbery after pulling a knife on a tourist.