BRYAN Cranston has revealed what all that meth was really made of on the set of Breaking Bad.

In an interview with Kyle and Jackie O on Kiis FM, the man behind meth manufacturer Walter White said despite using an innocent substitute, the cast and crew still got hooked on it.

“We use cotton candy flavoured rock candy,” Cranston told the radio duo of the impostor crystal meth.

“It’s vile tasting pieces of sugar. And in the 16th, 17th hours some days of working on the show I first noticed Aaron Paul taking a handful of products that we were making and he’s eating it and he’s like ‘I just need some sugar, I’m crashing’. I tried it and then pretty soon the entire crew was eating the sugar because we’re all exhausted and we wanted the sugar rush to get us through the night.”

Cranston, who also stars in the newly released Godzilla, said his role involved “method” acting of sorts and that he actually learnt how to make the illicit drug from chemists at a drug enforcement agency.

“They taught Aaron Paul and I the steps on how to make crystal meth at that level of purity ... they didn't want us to write anything down but it was so detailed that an hour later, I’d already forgot about the orders of things and I forgot the name of things. You really have to be a student of chemistry to be able to do it really well like Walter White made it.”

But despite the mega success of the program, winning ten Emmy Awards and two Golden Globes, Cranston said no one realised the show would reach the dizzying heights of success that it did.

“When we started Breaking Bad six, seven years ago, we were just a little show on a small network. We had no idea what was going to happen with that and we’re just trying to sell our story the best way we can and it took hold, and people were relating to this man ... and then it went crazy and there’s this mushroom cloud of attention and we’re grateful for it but it came as a surprise to us.”

In early 2014, Breaking Bad entered the Guinness Book of Records as the highest rated show of all time.