Mary T Moore / flickr creative commons From ancient scrolls to modern toner cartridges, ink (in one form or another) has been around for millennia. And while we may take it for granted now, for much of that time, it was a precious and coveted substance. Ink makers closely guarded their recipes; spy agencies developed secret, invisible ink formulations; and even now, billions are spent to create the perfect printer inks. This hour, we look back at the history of ink and ask whether its heyday might be coming to a close.