They also tried bronze and copper as well (mainly for money which used a mix of plate and movable type). The transition from wood to bronze metal type might ha

They also tried bronze and copper as well (mainly for money which used a mix of plate and movable type). The transition from wood to bronze metal type might have independent in Korea, though. They even had a pretty extensive printing industry as far as we can tell but it was fully controlled by the state/emperor and non official printing was illegal. I'm certainly not an expert but at least in China's case the type of inks they used didn't really work well with metal or even ceramic type which probably made the process relatively inefficient. Butyeah, Guttenberg invented a new alloy, ink, moulding method which made the process much cheaper and more effective.