No so fast

It sounds like a joke.

What was the mask that that man in the Iron Mask wore made of?

Although the story has been told and retold in the centuries since the real life events which occurred in France, 1669-1703, the actual answer is velvet. The reason most people assume iron is down to the poetic license of the storytellers of the day, which gave the whole episode a title of it's own which bore the literal description of his unusual facial garment.

Identity finally revealed in 2016

Eustache Dauger was a valet in 1669 and was arrested in unusual circumstances. It is not known who he actually was a valet for, but the terms of his arrest were suspicious to say the least. They dictated that he was to wear the mask permanently, never be allowed to meet or interact with other prisoners, and if he ever were to say anything other than related to his direct needs, be immediately executed.

Ordinary prisoners would not be subjected to such treatment, and there has been much speculation regarding his true identity, such as him being the illegitimate older brother of King Louis XIV of France, who could not bring himself to just have him executed. It was said he did receive visitors, but again these were all extremely secretive. He was given good food and even allowed to play a guitar in his cell.

Another theory goes that he was a valet for Cardinal Mazarin, a treasurer to the King, and knew he had stolen a great fortune from the King, so using this wealth the Mazarin ordered this treatment to silence him.

The 2016 research shows the prisoner was very likely to be Dauger, but not conclusively.

Voltaire was the first to dramatically, but unfortunately incorrectly, describe the mask as made of iron, and as we all now know it was nothing of the sort. Not only that, but he probably didn't wear it all the time - only when outside his cell, which was rare. Velvet masks were fairly common at the time since they were a popular accessory to shield people form the sun.

The news of the existence of the prisoner only came to the attention of the public when he was transferred between several prisons in the years following his incarceration.

Following his death in 1703, the walls of his prison were scrubbed clean and everything he owned was incinerated.

The cover up was complete.