Twenty years ago, Slipknot were considered a menace to society. Today, they release a new album – their sixth – that proves the world at large has caught up to the sound of their rage. Fuelled by loss, depression, desperate times, demagogues and demons, 'We Are Not Your Kind' is the band's greatest – and angriest – album yet. As the band tours its Knotfest roadshow around the States, Dan Stubbs talks to founder member Shawn 'Clown' Crahan and guitarist Jim Root about masks, metal and the making of a masterpiece.